20x20 v-Slot Corner Joint

I wanted to build a 4 post rack for small components using left over 20mmx20mm v-slot railing. I designed this to allow me to do so. Each rail should be able to be "locked" in place with at least 2 screws and I also recessed the screw holes so they should be flush with the corner joint surface.

The screw holes are designed for the circular 10mm screws.