Surely this should read "what have you done?"
I agree, and don't call him Shirly.
What have you made?
Yes, that also makes sense, added.
Present Perfect - no precise time context:
Co zrobiłeś? - What have you done?/made?
Simple Past - known (or implied) precise time context:
Co zrobiłeś (wczoraj)? - What did you do/make (yesterday)?
I put "What were you doing?" which is I guess past imperfect. What would that translate as?
Co robiłeś / Co robiłaś
Co porabiałeś / Co porabiałaś (in the sense of: what were you up to?)