I'd seen a thread asking for homemead tool submissions but cannot find it right now.
I made a homemeade putty trowel with a plastic hot dot/hamburger bag tie. I used it and liked it but it might be better glued to a popscicle stick. It's got many different shapes molded right into it, can be reshaped easily and they're free if you buy buns.
" alt="Putty trowel" />
" alt="Trowel finished" />