Interlocking 2020 Corner Bracket Feet

I needed feet for my Hypercube project and was to lazy for threading holes in the extrusions. So I designed corner Brackets with 4 holes and feet which also add stability to the frame,
Bonus: If you put them on top of the cube or whatever you make with those, you can stack an other element on top (see pics).
There are 2 Versions. One with deeper holes for shorter screws.