I printed J_T_3_D's Affordable Rock Tumbler and had quite a bit of trouble with traction. Since I didn't have a drain pipe on hand, I printed this part myself as well. The printed pipe only turned when a lot of weight was added. So I came up with the idea of converting the drive completely to gears.
I left out the pipe completely and inserted the TPU insert directly into the gears. The gears sit loosely on the insert and centre themselves on the drive wheels thanks to the herringbone. Alternatively, they can of course also be fixed in place with a little glue. However, this makes replacement more difficult should this ever become necessary.
The additional lips on the inside of the insert cause the material to move much more. I can't say anything about the durability yet. Time will tell.

I had some Benchys I used for a first 14h run. I put some small brass and steel wood screws in. The results are amazing. Looks shiny and and the touch is very smooth.