I calibrared my 3D printer to be square and to have proper dimensions in all axes.
I am going to start printing the parts for a LR2 in a few days. I saw that e.g. for Prusa MkIII there is a sort of calibration part, that is like the final confirmation that the printer is setup properly and that the parts will fit.
I do not think there is one for the LR2 - but which part would you recommend to print first and inspect for print issues? Not that I expect any. But I would like to print the most difficult/critical part as the first one - if there is any.
There is a 3D L shape, that is 100mm in X, Y, Z. That will save some plastic and you can tell if your build is square. There aren’t many interfacing parts, so the S fit test isn’t necessary.