Thanks JK3!
Anyways, I figured out how I am going to finish up the jump jet pack, I dont understand why my tiny brain couldnt figure it out any sooner. Im going to fiberglass the interior of the thing, make it solid all around, and reinforce connection points where the hotglue is.
For the thruster housing, instead of just trying to find a cone shape cup/object, Im going to form a ribbed series of semi-circles, starting with the largest at the top, proceeding down in size to the bottom part, where the nozzles will connect to. After the ribbs are in place, I'll take a styrene sheet and a heat gun, wrap it over and form it.
Did this for making a 1:1 scale horse prop at my school's theater, cant belive I forgot about this.