Your helo really turned out nice.
When making a "one of " it is always easier. When making things knowing that they will be cast opens a whole other direction in building.
This would be a relatively big casting project.
My guess would be 2-3 x 2 gallon units of RTV. @ $267 a unit.
It also would have to be totally torn down, made so that the pieces interlock and smaller pieces taken off and made so that they could be re- attached and fitted in place.
Possibly doubling the build time.
Sorry for being a wet blanket , but I have done a few projects this size.
My Tiger II project took about $1200 worth of RTV and about the same for my flying wing project.
Not to mention the time it takes to build the molds then start the pouring process.
Making smaller parts is one thing making molds as big as a bread box is something all together something else.
But it does look nice .