Introduction: Pocket Compass

About: I love coming up with quirky solutions to everyday problems. From the great state of California (Go Bears!), I am a professional engineer (according to text on my diploma). Instagram plug: Simplicity in name…

Using a compass has always been a challenge for me. The utter frustration arises when the compass moves midway through the circle, resulting in a half defined oval. Worst of all, those expensive "fancy" compasses are built to impale the metal bit into the piece of paper in order to have a stable footing, only to create a hole in the surface underneath the paper. Overall, most compasses are not meant to travel in someone's pocket (especially womxn's/children's pockets). The only other pocket compass that we found on the market was out of stock :(

The goals for this compass are as follow:

1) Minimal amount of materials needed

2) Does not require extensive knowledge of woodworking, metal working, and/or soldering

3) Fits into majority of pockets

4) Will not break while in the pocket

5) Takes less than 1 day to make (3D printed time included)

6) Can draw a 11" circle (since I typically draw on a 8.5"x11" piece of paper)

7) Takes less than 30 minutes to design in Solidworks (reduces the chance of making the overall design too complicated)

8) Gives me an opportunity to learn something new


- 1 bolt (diameter was 0.161 inches; Reader's discretion on bolt and nut sizes. Remember to change the diameter of the holes in the holder and slider CAD files. If you forget and the hole is too small, you can always use a drill to remove the unnecessary filament. If it is the other case, I recommend reprinting with a smaller hole.)

- 1 hex nut (needs to fit onto bolt)

- 1 washer

- PLA filament (*for the sake of transparency, I used a Monoprice V1 3D printer and 1.75mm PLA filament. The filament was on the cheap end. Even with the failed prints, I definitely used under 100 grams for this project.)

- Toothpick (optional)


- Screwdriver

- Pliers

Step 1: Getting Measurements

My two cents on the pant pocket debate of 2020. It is ridiculous that womxn's pockets are smaller than mxn's pockets. As a guy who specifically wears pants/shorts with ample pocket space, I would find it extremely difficult to store the amount of tools, gadgets, and random screws that I normally carry. Any ways, MEASUREMENT TIME!

Here are the detailed pocket dimensions for shirt pockets:

  • Womxn/youth (s, m, l): 3.5" x 4.0"
  • Mxn/unisex (xs): 3.75" x 4.25"
  • Mxn/unisex (s, m, l): 4.0" x 4.5"
  • Kids (all sizes): 2.25" x 2.0"

Pant pocket sizes are a bit trickier due to variations between and within pant types. If you are interested, here is a detailed breakdown of pant pocket sizes from The Pudding .

For the sake of simplicity, I went with 3.90" x 0.75". Having the length be close to 4" would allow the compass to fit in majority of the pockets. As explained later, the 3.90" was the ideal size as I was able to maximize the radius of the circle the compass could make.

(Photo credit:

Step 2: Note Down Compass Dimensions

I did this step while making the CAD files (next step). Writing down the dimensions and making a 2D mockup greatly help in reducing the chance of making a mistake. I tried to reduce the thickness of the compass, as much as possible. I wanted the overall profile to be inconspicuous, while in the pocket. Additionally, I wanted to use different pencils and pens with this compass. A thinner profile allows the nibs and lead tip to touch the paper.

Step 3: Make the CAD File

This design was easy to mock up in CAD (took 29.4 minutes). I used the default fillet value of 0.10" (Note: this is my CAD software's default fillet value. Yours might have a different default value).

While CADing up the designs, I realized that in order to maximize the radius, I need to design the base to be 3.9 inches. The extra space allowed for structural support around the holes.

I have attached three versions of my CAD files (.STL, .SLDPRT, .DXF). Unless you wish to make modifications to the parts, you only need to download the .STL file.

Step 4: 3D Printing Time!

Use whatever slicer your 3D printer comes with and upload the .STL files. Personally, I use the Ultimaker Cura version to convert my .STL files into .Gcode. By the way, .Gcode is the file type used by most 3D printers. Overall, the print time takes around an hour (at most 2.5 hours if your printer has a smaller extruder nozzle or other limitations).

Step 5: Assemble!

Make sure you have all the parts in the photo above for this step. You will need the bolt, washer, and nut but again those dimensions are up to you (I used whatever I had laying around the workshop). Additionally if you need to clean up the holes, I recommend using a small little drill bit (around 0.08" in diameter).

To assemble

First, push the nut into its slot in the slider component (using pliers on the edges ensured the nut was fully inserted). Then just add the holder, followed by washer and bolt, and screw the bolt down through the center hole in the slider. That is it! Less than 5 minutes to assemble.

Step 6: Completed Compass

Congratulations if you made the pocket compass! As an added option, I used a toothpick, instead of a pencil/pen, to be the pivot point of my compass.

How to use the compass

The way to use this compass is to extend out the slider to the radius of the circle you want to make (use the pivot point and one of the holes on the slider to find the radius). Using a screwdriver (I keep one on my keys), tighten the screw down to lock the slider in place. Now, all you got to do is put a pencil/pen/toothpick in the pivot hole and a pencil/pen in one of the holes in the slider. Hold down the pencil/pen/toothpick on the pivot hole and rotate the device around the pivot point. Once you are all done, just untighten the screw and push the slider and base together.

Step 7: Final Thoughts

So the pocket compass achieved all of the goals that I set out to achieve. This is perfect for a one day build (total time spent: <4 hours). I have been using it for a couple of days and so far the compass has not broken apart while in my pocket. Oddly enough, this device also works well to push elevator buttons.

One improvement that I might try is to remove the nut and bolt, and make a different clamp/holder mechanism. That portion of the compass does protrude out more than I would like.

Anyways, have a great day and subscribe to our Instagram account: @nutshell_engineering. We will be posting our failed 3D prints on that account. Have a great day!

Pocket-Sized Speed Challenge

Participated in the
Pocket-Sized Speed Challenge