1. FlareGun:
The flaregun allows the user to chamber rifles into the flaregun as if it was ammo. This can be easily replicated by draging any kind of rifle or pistol onto a flaregun it will say "attach 'AKM' to flaregun" or something of the sort.
2. Vests:
Vests can be put into your backpack and stuffed with items. To replicate try taking a highcap vest, drop it in your backpack, then pick up an item into your hands and hit the red 'X' to drop, it will be forced into your vest. only works if the rest of your inventory is full.
3. GasStoves:
GasStoves can be incepted infinatly. first assemble a stove using a pan, stove and canister, then add another stove to the pan and repeat.