A detailed assembly Manual for Rel 3. also with first steps for assembled printers is available in English and German!
Please download here: https://caribou3d.com/en/content/9-build-manual
Compiled firmware is available here: https://caribou3d.com/en/content/10-caribou-mk2-mk25s-mk3s-software
Source code is available on github: https://github.com/Caribou3d/Caribou-Firmware
Caribou 220 or Caribou 320 to Caribou 420 upgrade kit contains:
Linear rods (x,y,z) 8mm or 10mm
The 10mm version add stability and smoothness to the axes. The two short bearing on each side of the z-axis and the two bearings on the upper x-axis are replaced by a 55mm bearing.
The 10mm version of the kit contains in addition:
MK52 regular or block version
Bring the y-axis to a new level. The bearings are contained in aluminium blocks hence they can be easier aligned and run smoother. The MK52-block version contains: