Raspberry pi camera Base for wider build plates

Added 3mm to the Base gap, to accommodate the glass build plate I just got.

I've been using this mount for a while. I'll point out one trick I did. I printed the arm in PLA, and hit it with a heat gun, then molded it to the position I wanted. On my duplicator i3, the stock arm looks right at the x axis stuff 90% of the time, so I moved it farther back, and lower.