Small Machining Vise designed around 20x80 Openbuilds Rail System

I have the demand to cut/etch tall pieces of material. For this reason, I have designed a machine with 500mm uprights with adjustable gantry height. This way I can raise/lower the sled and z-axis as needed. I've also chosen to use a linear C-channel assembly for the Z axis with the plate mounted to the gantry instead of the other way around. This will allow for maximum range of the z-axis. The parts list/BOM does not include motors/belts/pulleys or electronics.