Trainman2001
I understand your frustration with the price of castings but I would urge you to work out a business case before you jump in. A few years ago I decided to create modular building castings in resin. Notice I no longer offer those kind items today.
Mold material cost $145 for a 10 pound kit. But first you need to create a master which for each mold type. An 6" x 12"x1/8" stryene sheet cost several $ and that is only for the master base. Add on the cost of materials to make the master itself plus the time to make it. The resin cost $125 for a 1 gallon kit. So your first cast panel will cost you easily 300$+ to make + your investment in time.
When your master and mold are completed I can tell you from years of experence that It will take several attempts and master reworking to get a satisfactory wall panel. One little air bubble will negate your sucess
If you need six panels for you engine house, each panel would be easily $50. Compare it with the cost of a modular building drawing at $6.00 each or whatever someone is selling a wood or resin panel for and I think you will find buying to be a less expensive and time saving solution.
Les Lewis