As an apocalyptic survival game, Unturned's lack of much viable makeshift gear is a travesty. This is kind of a general suggestion, but I think this game could use some more makeshift items (weapons included) to spice actual survival (versus b-lining to a military base) up a lot.

One suggestion to go along with this one: a makeshift muffler rebalance. I know it shouldn't be too good as it is a crude copy of reasonably advanced gun tech, but it is so utterly awful that literally almost no one uses it.

(I may add more specific suggestions of the same theme in the comments once I think of some).