new project... i have a few questions

[beastmode986]

ok so ive decided instead of a semi automatic airgun that shoots .357 ill have it shoot .68 paintballs. i want to make it look like an ak47 and m16 type combination i would make the body out of sheet metal.
now i know spoolies are probably more difficult to make than a poppit so im going to make a poppet valve style paintball gun.Spyders seem to have the simplest design but if anyone has anything simpler i could work a blowback looking action into please let me know because on the spyder i would use the blowback from the poppet to make a slide go back.
when i played paintball before i knew around 3/4 on how a poppet valve works but i want to fully understand so where can i find info on how to do this . also i want to have it powered off of either a 13/3000 guerilla or a 68/4500 but i want to make the tank also be the stock kind of like how the rap 4 m16 stocks are.
Before i get into any more detail can someone please give me a good source with alot of info on poppet valve paintball guns.Also is a poppet valve the simplest type of semi automatic paintball gun i can make that could have a blowback action?Also instead of making a bolt and stuff i would buy a regulator and asa and bolt unless a homemade version is cheap and more efficetive i want this to shoot around 280 fps or less so i can use it on the field. once again are there any flaws you can see in this plan?