Resident Evil weapons (airsoft)

Hi guys

i'm a big Resident Evil fan, and i was thinking of making an airsoft (if possible) of the flamethrower from Resident Evil (original)/RE2 which are both based on the m240 flamethrower from Aliens, i was thinking of using the upper reciver from a m16a1, and for internals a mac 11 or a mac10 with an extended barrel, for the trigger to trim it as flat as possible to the under body but have it still work, for the mag have it hidden inside the fake fuel canister, and with some parts added for more details, but the flamethrower from RE remake i'm having a difficult time to figure out what i could use to make the body, and like the other one, the mag could be stored inside the fake fuel canister (if possible) maybe use a aeg for internals, what would u guys think is the best way to do it?