I've been admiring all the stunning craftmanship in the Look What I Built forum - those models are positive jewels!
But I have to vent, guys, those flat wimpy stock propellors are a jarring note, especially when you've taken the time to add extra gear struts and rigging and pitot tubes to add realism.
Fixing those props is easy and doesn't require extra printing or photoshopping (well, extra printing is required for the models where only one prop side has been printed, because you need both sides of the prop).
Simply cut the blades free from the hub, but not where the blade joins the hub, but deeper down, because you need some root shank to glue the finished blades into the spinner (or to wrap the hub of a two-bladed prop around). Curl each blade face longtitudinally, with extreme curl at the root and some curl at the tip. Then glue the two blade halves together, so that the root forms a perfect tube. This is the shape of a real prop: thick and massive at the root, tapering out to a thin airfoil at the tip. (Keep in mind that at high RPM, the tension stress on the blades of a spinning metal prop is roughly equivalent to using the prop to pick up a 50 ton railroad locomotive, so the blades HAVE to be big and beefy at the root).
For props with spinners, punch holes in the spinner and glue the shank ends in, being careful to give the blades a bit of twist for pitch. For two bladed props with tubular hubs, simply wrap a small rectangle around the shank ends to form the tubular hub, and wrap small strips around the hub ends to represent the hub collars. Punch a hole through the center & glue the propshaft in & voila, a perfect propellor.
I think you'll find this touch, for not a lot of extra effort, and no skills beyond those already needed for the rest of the model, will add significant appeal to the finished model.
Of course, the really smart modellers will just slap on a clear acetate disc and be done with it - that looks great too.
OK, done griping - back to admiring those magnificent models!