I will take you disbelief as a compliment, Here is a couple of pics for you.
3 x pieces of flat, glued together then shaped accordingly, will make each rotor/port section, a total of 7 sections = 21 pieces to make the bulk of the engine.
Then its a matter of adding the rest of the appropriate bits and pieces so i resembles the 20B. (It is NOT perfect, i know this, but it was my first scratch build, and the first non-V8 i have built in over 30 years.)
Cheers, Dale