Crimp Strength Trainer

This is my take on a crimp strength trainer.  I have big hands and it allows for 2 or 3 fingers - smaller hands might get 4 in there.

I have provided 4 sizes that I thought work well for my needs:  a 15mm open and 12mm, 15mm, 20mm closed backs.

These are designed for use with a 6mm rope, but should work fine with smaller.  Just note that a smaller rope will apply a more contentrated force on the print.  I made a loop and fed it through.  This lets me easily choke weight plates or a pull-up bar.

Printing:

Print on it's back.  I recommend ASA/ABS (maybe PETG) with 7 walls and 25-50% infill.  Layer height and top/bottom layers don't matter too much with these settings.  Check the slice preview to ensure there's no gaps between the edges (see screenshot).

I printed the open back in ASA with 7 walls (grey model).  It's super strong.  I haven't hung my entire weight on it yet (mainly as I can't hold that) but I'm sure it'd be OK.

The other 3 are all in PLA with 5-7 walls.  They all seem adequately strong but not as strong as the ASA.

Safety:

I've tested these with up to 20kg of weight and they seem fine but I can't guarantee the strength of yours - it depends a lot on how you print it.  I recommend testing them before loading with to much meight.  You really don't want plastic bits stuck in your finger.