I made this up to hold my commonly needed allen keys and wrenches while I modified my Tevo printer. Easy to print with no supports needed, just print it upside down. I added a couple extra spots for tiny drivers I've found handy. It's not under any load so 20% infill is good. You will need one screw and tee nut to mount this.

Edit; I did a quick update to widen the wrench slot.