I was really struggling to solve the Half Cut packing puzzle by László Molnár (https://www.thingiverse.com/thing:4766223) and I read a hint somewhere that the cut half cubes should be treated as if they were solid.

I made an equivalent set of puzzle pieces with the cut cubes as regular cubes and then set about trying to solve it which, for some reason, in this form seemed much easier. With a solution in hand, returning to solve the original was trivial.