Edge tracing wheel.

thingiverse

This was one of my early designs, I've just honed it a bit more. I've swapped out the rubber bands for a pen clamp instead. A bigger wheel is now included, just in case it doesn't run smoothly. This design is meant to be used for tracing the edges of paper or wood and so on, to enlarge or shrink dimensions, the wheel follows the edge and the pen draws the new line. Print out all the parts, assemble them as shown in the pictures (the V groove in the axle lines up with the pen holder) - it should click into place nicely, but glue if needed. Use split rings to secure the wheel on the axle. (Add more split rings for even better grip.) The split rings move around to let you position the wheel exactly where you need it, and the wheel is reversible if required I used Loom bands to keep the pen in place, but rubber bands work fine too. 0.2mm layer thickness 0.8mm walls (two shells) 15% infill