Back in the eary 90's at Ford, we used some of the first SLA machines from 3-D Systems to build dyno intake manifolds. They weren't wet (EFI engines) and only held up for a few dyno runs, but were a great development tool.
The production manifolds were usually nylon, with some glass fill for stability. Of course we know about Chevy LS engines and some Ford Modulars with nylon intakes developing leaks over time. Not quite perfect...
