FSR 350mm bed remix

This is a quick remix of kevinlo's excellent FSR mounts. I used his mounts successfully on my Kossel Mini, however I needed something to handle the much larger bed of my Monster Kossel project, which has a 350mm bed.

Also, I put Ultibot's silicone pads between my FSRs and the bed because I like not heating up my FSRs... Those are 2.5mm thick, so the remix includes a higher ridge to account for that. The height difference is 2.4mm to make sure there's a little bit of wiggle room to account fo