Nope, too much of a pain in the butt
The rear exhaust nozzles need to be thickened in the master to give them more strength. They are just too brittle with this stuff to be trusted.
In other variations of the jetpack mold, I have tried reinforcing the same area with wire while casting but once again, pain in the butt.
Some parts seem to always be troublesome, even if I try to mold them in various ways. Cw arc parts are like that.