This is the file of a simple gear clove, you can scale in little or big as you want. If you print it 6 times the same file, you'll be able to assemble a complete gear, even in a very big scale as shown in the picture. Easy to print, flat with a little support.
All the best!

PLEASE NOTE: I add a new release "ingratenon.stl" with tenons after the request of Tibuck: you have 3 joints for each side, calculated with tolerance 0.2 - the little tenon must be printed twice. No problems with the internal overhangs, even if the bottom surface will be bad you can always join everything with bicomponent glue or epoxy.