My wife is an artist, and sometimes wants to draw large circles on a canvas. So I made her this beam compass. It uses a $1 Lowe's Wooden Yard Stick as the beam. (Lowes Item #22079 Model #30060)

You will need these parts:

• 1x Lowe's Wooden Yard Stick (6.4 mm x 36.4 mm cross-section)
• 1x 4d 1-1/2" smooth box nail (or something close)
• 2x 4mm nut
• 2x 4mm x 20mm socket head cap screw (1x 16mm and 1x 20mm is ideal)
• 1x 4mm washer
• and a pencil

To install the nail and the cap screws, I heated them enough to melt the PLA and then pushed them into place. They all retained nicely that way. Or you could drill-out the holes a bit and then glue them in.

If you want the imprinted yardstick measurements to indicate the radius of the circle, then cut the first 1 inch off the yardstick. (Or keep the yardstick full length and subtract 1 inch from from whatever is indicated.)

If you have a 5 gallon paint stick, try this design instead https://www.thingiverse.com/thing:4321817