How to make an infinite mass solid body

I have an object that I want to control directly, but I need other things to bounce off of it. Just changing the position doesn’t make them bounce. Presumably because it has no momentum, so they don’t get energy from it. I don’t want to give it solid body physics because I don’t want it to react to collisions. Should I give it infinite mass? Is there a better way to accomplish that?

I don’t understand clearly what you are trying to do, but you can have an object which uses physics (and bouncing properties) which doesn’t react to collisions if you set it to be kinematic.