You may want to address this ahead of time. You certainly don’t want to start with an .stl if you can avoid it. You will want a solid body. You are machining. 4th Axis simultaneous machining to be specific. It will take something akin to Fusion 360 (with full license) to do this successfully. .stl’s are for printing. Converting high quality, high detail .stl’s to solid bodies takes a lot of computer processing and creates enormous files that can cause issues.
I plan to build a Fantasy Battle Chess set with the 4th axis when I can order one. I have no files as of yet, but don’t plan to start with 3d prints and work backward.