The LEGOs themselves are coming along nicely. Be sure to print the calibration blocks and set the top_tweak and bottom_tweak numbers appropriate for your printer and plastic. Then you can tune the fit quite precisely. It was interesting to find that 0.02mm increments on calibration blocks were not sufficient- we had to drop down to 0.01mm steps between calibration blocks to dial the fit in exactly. Example numbers from a Taz 6 are provided in the Customizer comments and OpenSCAD source.