I forget what they are called ATM, but the naked challenge ones have 10 arrows at the start. You can spend a few minutes every BM and get 40-50 arrows for free. These are also some of the only sources for mid level constructs if you’re upgrading the relevant armor. The ones with the right constructs also have decent extras like spiked iron balls and stuff.

Edit, nm you mean that other stuff.

Can you shield mount the giant bouncy balls?