The ruins: A friend of mine designed the ruins in a 3d computer modeling program, and then had the resulting "master" pieces produced using a 3d-printer. Then he made a RTV mold of them, and cast a bunch of pieces in dental plaster, for use in Warhammer 40k.
Fast forward to last year, I was doing some resin casting, and had oodles of resin left over, with no planned casting projects in the future. I didn't want the resin to go bad, so I cast a slew of the ruins using my friend's molds. The result is on the graveyard board!
The 3d-modeling stuff is neat, and 3d printing is getting cheaper and cheaper every day. With that said, my friend tends to over-engineer most hobby projects (unsurprisingly, he's an engineer), and tends to go with high-tech solutions to problems first. Often, though, the results are spectacular!