I was having lots of problems with this one. I tried to create 30 different types at the crafting station, and I probably made over 100 bombs at the crafting station and still nothing. Turns out, the ones you make at the station DO NOT count! I stood at the station, built one of each of the three types, then quit the station. Then if you hold the RB to open your item select, use the right stick to point to each of the three and use X or Y to craft from inventory. Then simply open the crafting station back up, break down your recently crafted bombs, quit out and create from inventory again.
After I crafted them on the fly like this, the achievement popped right at 30 (not 30 unique, I only made 3 different types here).