There already is a lot of weapons out there that you could use for a TF2 mod. There is a chaingun, sniper rifle, pistol, I think a grenade launcher (If not, it would be easy to do), I think there is something you could use as turrets (A bot maybe?), I think there is a rpg (If not, it's another easy-to-make item), shotgun, and you could use just about any gun for the medic. It would be nice if someone made a flamethrower and a healing gun (If the healing gun is even possible). You could make the decals on your own and the hats would be easy to make. Maps are a bit tougher though.