Print 9 rotors and 1 housing. You may want to do one rotor first, to try the fit.

Clip the 9 rotors into the housing, fit the centre one first, then the centre column, lastly the outside columns. This is because the housing has to flex a bit to get them in. The notches in the rotors are to make it a bit easier to get the rotors in the housing. Try and push them in square and then carefully turn them a good few times to ease them in to working correctly.

I printed them on my UP! using default settings, in ABS and they worked out pretty well, although I had to work the rotors a bit to bed them in.