u/Ill-Environment8198

I wanna make a speedsoft hpa gun like one of these but don’t know too much about them and had a some questions. which do you guys mostly prefer? a tank line or the tank connecting to the grip? also i prefer the crbn upper frame, i think those ones look rlly cool and i also want an f2 engine on my build but what else is good with what i want? should i just buy a stock gun and upgrade it to be like one of these? or build it? and if so what airsoft guns can i modify to be and look exactly like the ones in the pic?