Despite your points being right about a Cast being more cost effective. You can indeed 3D print metal. You can 3D print Platinum, Gold, Silver, Bronze, Steel, Sandstone, Porcelain, all with different smoothing finishes… The list goes on! Needless to say its expensive. Not as cost effective as your solution.
I hope you get orders or the motivation/funds to do more work.
You seem really low on funds based on your earlier comment
Why don’t you offer one of the services you have used for commercial games to build up funds to inject more money into this?