Just a few off the top of my head :
Weathering on a budget, using common household items and easy to get stuff from craft stores;
Easy installation of individual track links for tracked vehicles, with how to make an universal jig;
Kitbash and scratchbuild a “what-if” vehicle just for fun, using kits you won't use anyway;
How to do convincing damage, from a small dent in the fuselage to a huge hole made by a 155mm shell;
I may have more if I think a bit harder !