Soundproof Enclosure for the Monoprice Select Mini 3D Printer

The Monoprice Select Mini printer is an open design, all noise making parts are exposed, and as the stepper motors move the head and the platform, the vibration transfers to the table it is sitting on. There are a few sound proof enclosure designs on the internet, but I have found one that looks cool and easy to assemble. The original design doesn’t use the lid as a platform, but as I found out, the lid on flexible legs and the soft foam insulator under the printer greatly reduces the vibration transferred to the table. My family doesn’t even notice anymore when the printer keeps working overnight on a large model. Without the enclosure, I always had to make sure the printer stopped before bedtime.

The enclosure provides significant noise reduction. I have used an iPhone app to measure the noise from 1 meter distance. The 6dB difference doesn’t look too much, but on the logarithmic scale that means half volume reduction.

  • Without the cover: 39 dB
  • With cover, door open: 34 dB
  • Door closed: 33 dB

I could not measure much difference in noise levels with and without the insulator on the door, but during night printing even a small reduction in noise level counts.

My version of the soundproof enclosure for the Monoprice Select Mini 3D printer is based on the great design announced by Daniel Smith at
The original build instructions are at

In this post, I will show the modifications I made to the original design. Read the original article for more information.

I re post the bill of materials in case the original article disappears:

The total cost of my version is about $150, though you can eliminate a few of the line items to bring the cost down if needed. Ended up not buying the web camera, as I can check on the progress anytime by walking to the printer. Maybe later I will buy it to create time lapse videos.

The extra items in the bill of materials above for my design:

  • Double sided 3M foam tape to attach the custom legs,
  • 8 thin wood screws to secure the blowers.
  • Elmers Glue and clear packing tape to secure the dome
  • 12 strong magnets to attach the insulator to the door if necessary.

The final product

The major differences are the transparent dome on the top and using the lid as the bottom of the box. The dome serves two purposes: Room for the tube at the top of the head, and provides a great view of the 3D object on the platform during the printing process. The lid provides the needed alignment when I put the box above the printer because the build platform almost hits the front and the back of the box.

Mark the openings

Measure twice, cut once told my father, and he was right. The original author already warned us, because the box sits above the printer upside down, it is very easy to cut the openings on the wrong side of the box.  I have started the process with a permanent marker and marked all openings on the box. Before cutting the material, I placed the box above the printer and verified the location of all of them.

The dome

When the head is at the highest position, the feeding tube needs more room than what the plastic box provides.

The transparent dome is the packing material of a large headphone. First I cut the opening for the dome with an electric jigsaw.

The air outlets

The distance between the hole centers is 15 mm, drill the holes with 8 mm drill bits.

Fan mounting holes

The original plan recommended Super Glue to mount the fans, I wanted a more secure hold, so I used thin wood screws to attach the fans to the box. To mark the location of the holes I inserted the screws into the mounting holes of the fans, painted the heads with the permanent marker and quickly pushed them to the planned location inside the box. After a few tries, I could see the screw locations on the walls. I enlarged the marks with a thick permanent marker and using a flash light copied the locations to the outside surface. To get the correct position I used small strips of the insulating material under the blowers because those will be on the surface of the insulator.

Speed controller

I drilled a hole for the potentiometer of the speed controller and used the nut to secure it below the power strip on the left side.

Power strip

Drilled four holes for the zip ties and cut a square opening with a Dremel tool for the plug.


Room for the build platform at the back

THe build platform almost touches the front and the back of the box. To make more room at the back I used the same Dremel tool to remove the ribs from the back of the box.

Printer power cable openings

To change the filament, replace the blue painter’s tape on the build platform, or remove a large object, I frequently have to lift the box. To easily position the box over the printer, I use the lid as the base under the printer. To be able to easily remove the box and place it on the floor, the power strip only provides power for the blowers and the LED strip ( I haven’t installed the camera yet ), I left the power supply of the printer outside of the box and plugged it separately into the wall outlet. I used a 5/8″ wood bit and the Dremel tool to enlarge the hole for the barrel plug.

I also drilled two holes for the cable tie to secure the power cord to the lid.

I also had to cut into the edge of the box where the printer power cord enters the box.

Easy lifting

To be able to easily lift the box, I have cut the tabs with the Dremel tool on the sides of the lid where the handles are.

Cool air for the printer

The printer also needs fresh air to cool the control board inside. The Monprice Select Mini has openings at the bottom, so I have cut holes into and elevated the lid with custom legs to provide the air it needs. I used a sheet of paper to copy the exact location of the opening to the lid. The lines are 15 mm apart, and I used an 8 mm bit to drill the holes.

I cut strips of the insulator to lift the printer because I had to pull it forward to provide enough room at the back for the platform. The left side of the printer is much heavier, so it needs more support there.

To provide room for the air flow under the lid, I had to print custom legs for the edge and the center to support the weight of the printer. The diameter of the legs is 30 mm. The height at the edges is 5 mm, under the printer 13 mm. I used the flexible TPU material for better noise reduction, and double sided 3M foam tape to secure them.


Cut the insulator

I traced the box to cut the insulator. For the back and side walls make the insulator larger because the turns need extra material. You can cut the excess after you have pasted it in place.

Secure the dome

My dome has a 10mm flat edge around, so I used Elmers Glue and transparent packing tape to secure the dome from the inside of the box. The insulator provides the additional support. I put the blower wires under the insulator of the back wall. Cut an opening in the insulator for the speed controller, do not hide it, because it needs air for cooling. Cut into the insulator for the output of the blowers.

Cut into the insulator where the build platform needs extra room.

LED lights

Install the LED strip above the door and hide the wire under the insulator. Use the USB outlets of the power strip to power it.

Door insulation

I left the protecting paper on the insulator for the door. I use 12 strong magnets to be able to attach and easily remove the insulator from the door. I hold a magnet on the inside surface of the insulator, and another one on the outside of the door. I could not detect significant noise level differences with our without the door insulator, but during night printing every decibel counts.


3D Printer GCODE instructions

GCODE is a standard file type to control 3D printers. The 3D object is usually exported from the CAD program to an STL file, that fully describes the end product. 3D printers build the physical objects layer-by-layer, so we need to slice the object into thin layers.

Turn off the fan after 5 minutes

When the printer completed the job, the fan of the Monoprice Select Mini printer says on, making noise, and wearing out the bearing. To turn the fan off after 5 minutes, add this code to the end of every GCODE file.

G4 P300000 ;wait 5 minutes before turning off the fan
M106 S1    ;turn off fan

To automatically append the instructions to every GCODE file, in Cura add the lines to the end.code section:

  1. In the Cura application select the Start/End-GCode tab,
  2. Select end.gcode,
  3. Enter the lines in the bottom window.


Create 3D models based on pictures

To create a 3D model based on a picture of the original object

  1. Start a 2D sketch
  2. On the Sketch tab Insert section select Image
  3. Browse to the image and place it on the canvas
    1. To move the image, drag the center with the mouse,
    2. To rotate the image, grab it in the lower left, lower right or upper right corners,
    3. To scale the image, grab it at the top or bottom edge. The aspect ratio is preserved.

Working with solid bodies in Autodesk Inventor

To move a freeform solid body

  1. Select the solid in the part drawing
  2. In the context-sensitive icon menu select Edit Freeform, or in the browser right-click the freeform and select Edit Freeform
  3. On the Freeform tab select Edit Form
  4. On the Edit Form popup page click the Body button
  5. Select the freeform solid
  6. Move the solid with the arrows


Subtract solids from each other

When you create a design where you need to mount an object on another, attach two objects to each other, or leave room for another object, model both objects and subtract one from the other. This will create the perfect interface for the connection.

Autodesk Inventor can subtract two independent solids from each other. The two solids cannot have any references to each other, so we cannot use the Project Geometry to project one of the objects to a plane to guide the creation of the other.

Create separate solid bodies

If the product is not too complex, it is easier to build the entire product in one drawing. Most of the time this will only yield one solid. The combine command requires at least two separate solids to work with, so to separate the parts of the design to individual solids

  1. Build the product with multiple parts in the same drawing,
  2. Save the combined design file as …_all_parts.ipt,
  3. Delete the part that represents the first solid,
  4. Save the file as …_second_part.ipt,
  5. Undo the delete steps, and delete the second part,
  6. Save the file as …_first_part.ipt,
  7. On the Manage tab select Derive and select the file of the second part to import it into the drawing.
    This step inserts second part as a separate solid.

Subtract the solid bodies

  1. Create the object that will serve as the “tool” to cut into the object,
  2. Position the object on the tool to cut into,
  3. On the 3D Model tab select Combine,
  4. On the Combine popup window click the Base button,
  5. Select the solid to be trimmed,
  6. Click the Toolbody button,
  7. Select the solid to be used as a cut tool,
  8. Click the Cut button,
  9. If you want to keep the cut tool in the drawing check the Keep Toolbody checkbox,
  10. Click the OK button to proceed with the cut.

Modify STL 3D printing files with FreeCAD

There are many free STL files are available on the internet to 3D print useful objects at home. There are times when we want to make some adjustments to them to better fit our need or 3D printing equipment. If the STL file describes an object that is larger than the maximum dimensions your printer can produce, you can print the object in two or more pieces and glue them together. There are glues on the market that can make as strong bonds as the materials themselves they are attaching together.

There are free applications that can open and edit STL files, one of them is the open source FreeCAD.

Download FreeCAD from

Open and edit STL files in FreeCAD

Import an STL file into FreeCAD

  1. Start FreeCAD and create a new document with File > New,
  2. In the menu select File > Import and navigate to the mesh file you want to modify. FreeCAD can open STL, OBJ, and AST mesh files.
  3. In the dropdown select the Part workbench,
  4. In the Model window select the imported mesh,
  5. In the menu select Part > Create shape from mesh
  6. The default 0.10 tolerance is usually fine for most of the objects we 3D print, click OK,
  7. Delete the imported mesh in the Model window. Right-click the name of the imported mesh and select Delete,
  8. Convert the shapes to solid. In the toolbar click the Advanced Utilities icon,
  9. In the Tasks window select Solid from shell
  10. Click one triangle on the object,
  11. Click the Create button. You will not notice any change because the solid overlaps the shape.
  12. Click the Close button in the Tasks window,
  13. Delete the shape. In the Model window right-click the name of the shape and select Delete. We have converted the mesh to solid, ready to be edited.

Edit the solid model in FreeCAD

  1. To add or remove parts, open the Part Design workbench,
  2. Select the Solid in the Model window, so the object turns green,
  3. In the Part Design menu select Create Sketch
  4. Select the plane you want to draw and click OK,
  5. Draw lines, circles, rectangles that we will extrude to add or subtract them from the object. Don’t worry if the sketch is not at the correct elevation, we will move the sketch to the correct elevation later.
  6. To print a portion of a too large object, draw lines and trim them at the location where you want to separate the object into multiple parts.
  7. To close and save the sketch click the Close Sketch icon in the tool bar.
  8. To continue to edit the sketch, double click it in the Model window.

To change the elevation of a sketch

  1. Select a face on the solid the move the sketch to,
  2. In the Part Design menu select Map sketch to face
  3. Select the sketch in the drop-down list and click OK,
  4. The sketch opens. You can continue the editing of it, or just close it.



Pause 3D Printing

There are some designs where you want to change the filament or insert a nut into the product. To pause the 3D printing process

  1. Export the design into a .gcode file,
  2. Open the. gcode file with a text editor,
  3. Insert the following lines into the file at the point you want to pause.
    ; Display a message
    M117 Change the filament and continue
    ; Pause the printing

If you want to print text, it is possible to pause the printing, change the filament to a different color, and continue.

To find the layer where you need to change the color in Cura, the free 3D print utility

  1. Load the STL file of the design into Cura,
  2. Click the View Mode icon in the upper right corner of the screen, and select Layers,
  3. Use the slier to navigate between the layers,
  4. Find the layer that prints the bottom of the groove, and write down the layer number. Note that the slider starts to number the layers with 1.
  5. Save the .gcode file to the disk with the Floppy icon on the left side. If the icon is gray, the design is larger than the printable size of the printer. You may scale the design down with the Scale icon.
  6. Open the .gcode file with a text editor,
  7. Note that the .gcode file starts to number the layers with 0. To stop at the correct layer, we need to subtract 1 from the number we have seen on the slider.
  8. We will change filament colors to print the bottom layer of the groove. In our example, layer 113-1 = 112 printed the bottom of the groove, search for the text Layer:112 in the file,
  9. Place a pause instruction before that line in the file
    ; Display a message
    M117 Change the filament and continue
    ; Pause the printing
  10. Find the next layer in the file, in our example, search for the text Layer:113 in the file,
  11. Place another pause instruction before that line in the file to change the color again.
    ; Display a message
    M117 Change the filament and continue
    ; Pause the printing
  12. Save the file and start the printing process.

Import STL mesh files into Autodesk Inventor

Import and export STL mesh files

To enable Autodesk Inventor to open and save .stl files add the STL Import and STL Export add-ins to Adobe Inventor. .stl files are used to transfer 3D print designs between computers. You can download most of them for free from the Internet.

  1. In the Tools menu open the Add-in Manager
  2. On the Translators tab select the STL Import and STL Export translators.

To be able to edit the STL mesh files

install the Mesh Enabler add-in

Download the Autodesk Inventor Mesh Enabler

  1. Navigate to the Autodesk app store at
  2. Sign in with your Autodesk account
  3. Search for Mesh Enabler
  4. Click the Download button

Install the Autodesk Inventor Mesh Enabler

  1. Double click the downloaded AutodeskMeshEnabler.msi file and complete the installation
  2. Start Autodesk Inventor
  3. In the Tools menu select the Add-in Manager
  4. On the Applications tab select Autodesk Mesh Enabler
  5. Select the Load Automatically checkbox
  6. Click OK

To convert an STL mesh file to a solid model

  1. Start Autodesk Inventor
  2. Open the STL mesh file
  3. In the browser right-click the MeshFeature1 element and select Convert to Base Feature
  4. In the dialog box select the output you need and click OK.

    1. Solid/Surfaces: Converts the selected mesh features to multi-solids or individual surfaces. To create solids, the mesh features must form closed meshes.
    2. Composite: Converts the selected mesh features to a single composite feature.
    3. Delete Original: Deletes the selected mesh features after conversion.

Set the default project location

Inventor saves the new projects in your document folder. To set a different default location

  1. In the Tools menu select Application Options
  2. On the File tab click the yellow folder icon next to Project folder and set the desired location.

To save the solid model as an STL 3D mesh

  1. Open the Inventor Parts (.ipt) or Inventor Assembly (.iam) file in Autodesk Inventor,
  2. Click the Inventor icon in the upper left corner,
  3. Click the small arrow next to Save As,
  4. In the submenu select Save Copy As,
  5. In the Save as type dropdown select STL Files,
  6. Enter a name for the file and click Options…,
  7. Select Source Units to make sure the size of the mesh is identical to the objects in the Inventor document,
  8. Click OK to close the Options window,
  9. Click Save to write the file to the disk.