Raspberry Pi rail mount

This is a project im working on to rail mount a raspberry Pi. I use the Astrobox interface with my RPI2 for my 3d printing needs.

Current model I have not tried to print, I printed an earlier design that i wont be releasing but it had a different mounting system using a slide in triangle feature. This ended up failing on the mount; the RPI fits into bottom fine but the top is rather snug with how wide i have the holes on the lid (this could be an error with calibration on my reprap) Let me kn