Roomba casters are a pain. Dust and hair gets stuck in the wheel shaft until they stop rolling, and there is no good way to clean them without breaking it. After my second replacement caster failed, I decided to design my own which would be cleanable. The original wheel, wheel shaft, and vertical shaft are all reused from the old caster.

There are a number of steps to build it.

1. Print out the new caster body from the .STL file attached.
2. Remove the vertical shaft from your old caster. I heated up the shaft by sticking it in my soldering iron and pulled it out when it was hot.
3. Install the vertical shaft into the new caster body.
   a. I put the original shaft into my soldering iron just like it was a soldering tip.
   b. Slowly heat up the shaft while gently pressing it into the caster body.
   c. Increase the heat gradually until it starts to push in, then don't go any hotter.
   d. Make sure the shaft is straight.
   e. Optional: Using a scrap piece of filament, melt plastic around the base of the shaft to hold it firmly.
   f. Use a sharp knife to clean up any excess filament around the shaft.
4. Use an M3 or 4-40 tap to make threads for the retainer screw that holds the shaft in.
5. Install the wheel and its shaft.
6. Install the retainer screw.
7. Stick it in the Roomba.

Clearances and tolerances vary from one printer to the next, the .scad file is attached in case you need to adjust those.