I've got this pull-up bar about 1.5 years ago. It's the cheap one where you can just put it on your door whenever you want. And I've noticed it's made dents on my door. So obviously I want to prevent this, but I'm not too sure how. I know if I continue using it, the dents will become worse. I see that the foam on the end handles where they're pressed against the door have worn down, so I suspect that the metal makes direct contact with the door frame, hence wearing the wood down.

The only solution I have to this is to put a sponge(dish sponge) on the bar so that presses agaisnt the frame, and protects it from the metal.

Any other solutions?