Yes, Tin Foil.

Tin Foil Platypus? Is it possible? Can it be done? Would it even work? Yes, Yes, and YES. I made one, and it hasnt fallen apart (yet...)!! It can be done! I can't really explain how, you just kinda get some tin foil and figure it out as you go along! :D What? You want to see a picture of it? Sure! Here ya go!

Sorry the the lighting is kinda weird and reflect-y on the platpyus, i guess thats what happens when you take a picture of tin foil!