How to design an injection mould for plastic cups

What is the best CAD tool to use?

2 Answers

Have a look at this. It might help you.:)
http://www.widom-assoc.com/derived_parts2.pdf

You can simply design the part and then go to the Mould environment which will help you along the way, For best results consider Mold Advisor for simulation and gate location.
With some tinkering you'll figure it in no time.