[Joey Milia]

A couple years ago 192 experimented with molding Urethane wheels. We tried both with fiberglass, based on the same posts you were looking at I believe [edit: Andrew linked to it below], as well as without fiberglass, based on 118's 2013 wheels. However neither project got to the point of testing the wheels on a robot.

We made the wheel masters first by machining a block of HDPE and then by 3D printing them. The molds were made by pouring silicone rubber around the masters in a mold frame. Then once the molds had cured we could pour in the urethane plastic. We used only single part molds so one face of the wheel would be rough and machined off after it was taken out of the mold.

We ordered all of our plastic from Smooth-On. They have a huge selection of different silicon rubbers, urethanes and anything else you need. We used Mold Max 30 silicon rubber for the molds, and Task 9 and task 3 for the bodies of the wheel. We also experimented with some urethane rubber for tread trying to copy 118 but we were less successful with that.

Smooth-on also has a bunch of videos about how to use their products that are really helpful when trying this stuff for the first time.

Let me know if you have more questions or would like more detail about what we did.