I'm just making my first foray into glass plate printing and I realised I needed to adjust the Z axis zero point to compensate for the thickness of the glass, so here's a little device to do just that. I designed it for my Wanhao Duplicator 4 which I believe has the same layout as the Makerbot so should work for either. Nice and orange so I can easily see when it's in place.The spacer is designed to sit on the 5mm thick vertical perspex plate which activates the Z-axis zero microswitch, tripping it 3mm (the thickness of the glass) earlier than it would without. When you put the glass plate on, just use the handle to lower the spacer down onto the rear plate, behind the Z-axis threaded rod. I printed this the slow way (vertically) to eliminate the need for bridging across the gap and to give extra strength to the handle. And my first print onto glass? . . . Smooth and shiny!