I've used these rubbers: https://amzn.to/4dnZbLg

But these should also work: https://amzn.to/4ba8gFW

You can also use the ones with 4 rubbers and just leave one empty hole in each side (I suggest the middle one).

I printed it with PETG, but after printing and testing, most probably PLA would also work. Let me know in the comments/makes.

Print HORIZONTALLY to increase strength/resistance.

• Layer height: 0.15
• Line width:
  • Default: 150%
  • First layer: 100%
  • Outer wall: 100%
  • Inner wall: 0
  • Top surface: 100%
  • Support: 100%
• Wall loops: 5
• Alternate extra wall: Yes
• Top shell layers: 5
• Top shell thickness: 1
• Bottom shell layers: 5
• Bottom shell thickness: 1
• Infill density: 50%
• Infill pattern: Cubic
• Support: Yes
• Support type: Tree
• Support angle 30