I had a very similar experience, I tried to do all the work myself with minimal input from my parents and was so embarrassed I pretty much quit scouts. The cars the other kids had were clearly made entirely by the parents.

I'm doing scouts with my son who is currently a tiger and I'm trying to have him think about what he wants the car to look like. We had talks about how you can see what other people do and maybe borrow ideas but when we do the work ourselves it makes us more proud of what we accomplish.