I just got an inquiry for a 3D scooby Doo cake. Before giving a word, can I do a scooby doo cake without a copy right issues?

I would say no you can not make a scooby doo cake, you can put purchased Scooby doo figures on you cake, if purchased by the person who ordered the cake. Scooby is a copyrighted figure. There fore you can not make and sell a scooby cake.

I thought so. I would tell the customer right away.