*** PING ***
I would think you could take the 3D version and make a sturdy latex and silicone mold of it and then pour in casting wax, then take the now hard wax piece and place it in a box of casting sand. There is a procedure or two involved but essentially you then pour molten metal into the mold which burns off the wax leaving you with a metal piece now, after that its just a matter of fitting the machined sections, a dremel can do most of it.
Usually the lost wax casting process involves pot metal of a soft type of metal. But there are other directions such as now making basically something out of carbon fiber, or an epoxy mix such as JB Steelweld. A lower receiver could work if it had steel inserts in key places, much like a Glock frame.
Went into Walmart yesterday to buy a couple boxes of Remington .223s, in prep for coyote hunting. Sold out. Then to another Walmart, sold out again. WTF?
Guess I’ll start reloading, never done that and don’t know if the components are even available.
lol