Can I get a single design patent for a design with multiple interchangeable parts? Let's say I design a hat with multiple interchangeable decorative parts. You could buy the base hat with some velcro or other fastening method and then buy various heads, tails and legs to change it's appearance. The parts would be sold in sets: a horse, a cow, a chicken etc.
Can I apply for one design patent for the whole system including the various parts? If so, would I need a new patent very time I added a new set of animal parts? Or would I have to apply for a separate patent for each set of parts?
I am thinking of Crocs with those little decorative buttons they attach to the holes. Would that have been one patent that covered that whole decorative shoe system? Would they have illustrated the exact design of each button prior to applying for the patent? And reapplied every time they wanted to add new ones to the line?
Thanks for the advice!