I print at 0.20 mm layer height with 15% infill on my Prusa Mk3 and it takes about 4 hours to print the plate of parts. There are two holes that ideally would be tapped for M5 screws - one on the part that holds the pencil, the other on the part that lets you clamp the compass open at a particular angle/radius. But you could also drill out those holes to 4.75 mm / 3/16" and then just gently thread an M5 screw in there and form the threads without tapping. 10-32 screws should be just about right, as well. Find a nail or screw and insert that into the end cap with a small hole in the end (you might need to drill it out a bit, depending on the nail or screw you find). This will serve as the point of the compass. A drywall screw or medium size nail is about right. Not critical, just make sure it's fixed (or that you can glue it in place) so it doesn't wobble around. Cut two equal lengths of 3/8" (or 10 mm) diameter dowel as long as you want. Mine are about 9" (225 mm) long. Assemble as shown. For reference, the center of the arched piece wants to be ~4" (100 mm) from the pivot point of the hinge so the mating piece that goes on the other leg of the compass works with the arc. Two-part, 5-minute epoxy works great for this assembly - it doesn't see huge loads, and you'll be able to use it quickly. But I also saw this as a fun use of safety wire pliers, and used some thin stainless steel wires to fix the plastic parts on the dowels. You can tuck the extra bits of twisted wire between the plastic halves as shown. An M5 x 20 mm bolt with a nylon lock nut works great as the pivot for the hinge. Another M5 x 20 mm bolt will help secure the pencil in the holder. I happened to have an M5 thumbscrew to lock the compass open at the desired radius, but an M5 x 10 mm bolt would be just as effective. Have fun!