Because I was never really happy with my first R2-D2, I decided to sell it and build another, more realistic one.
I purposely will not give any hints how to build a perfect R2 here because I do not want to invent the wheel a second time. You will be lost without professional help. This help you will get from the R2-Builders-Club. Membership is free and some people there will help you building some parts and you may ask for blueprints there.
Anthony Daniels, my R2-D2 and me: