27mm Piezo Underbed Mounts

I was looking for delta bed mounts for the [Precision Piezo](https://www.precisionpiezo.co.uk) system and came across RandomFactoid's, which looked great! Except that when I bought my kit, the 20mm discs were out of stock so I only had the 27mm version, which wouldn't fit. So out come the calipers, and a few hours of modeling and testing iterations, and here we are. Built from scratch, but using the critical measurements and design features from their inspiration.

Biggest change beyond the obvious is that I added another mm to the bottom to make the base stiffer, since they extend out from the rail a bit further. Did that need to happen? I dunno, but sacrificing one mm of z build volume to not have to worry about it was worth it.

The cap and plunger were scaled to the tolerances I could print, which give a good friction fit for the cap and free movement for the plunger. You might need to scale these slightly in your slicer.