Print all files with at least 3 outer walls. Better would be 4. Non structural parts can be printed with 25% infill and PLA/PLA+. For the parts taking weight i highly recommend PETG or ABS and up to 45% infill.
Parts with most stress are:
Shoulders & Shoulderhub
For all parts printed with TPU use 50% infill and 5 outer walls!
I put all my print settings for R2-D2 i built into this sheet:
Print settings sheet: