I've always wondered why there weren't more variants of the infamous MG42 since it was such a successful design, one that is still used today as the H&K MG3. The main modification I've always imagined is shortening the barrel and lightening the design, turning it into a SAW-style weapon like the M249. So I did just that:

1) Standard WW2 MG42

2) MG42K - Shortened barrel

3) MG42CP - Ultra-short barrel, a synthetic handguard and modified stock, and high-strength polymer parts to lessen the weight