About this 3D model

I saw prusa's excellent heated bed, but the dimension was too large for the blank stock I had available, and there were too many narrow traces for an easy home etch, so I designed a different one. Dimensions are 200x200mm, hole centers are 190mm apart. Design resistance is 0.95 ohms. Etch from 1oz (36um) copper to get this resistance. Gives 150w from a 12v source, and consumes 12.5A. I've had my bed up to 140°C before, and didn't want to take it higher for fear of cracking my glass or damaging the FR4 PCB material.