I have a first hand report on a roundhouse brick wall in HO produced in injection molded styrene. The bricks were reported to be the finest Terry Wegmann has seen in plastic. The walls were CAD 'ed by the increasingly productive Jim Booth, and the mold maker cut the tooling with a focused laser cutter into the metal mold.
Terry has been working with a Laser Tooling maker for 2 years to make molds for producing styrene SP Overnight doors (and 2 other improved Youngstown 10-0 6' doors), the mold maker patiently waiting for the CAD data to proceed.
I saw at Terry's work a large scale switch stand which went from CAD to SL to wax to investment part. No hand prototyping. Real Cool!
I don't see much time passing before complete laser cut injection molded freight car kits (& RTR) becoming available. The implications can be enormous- imagine freight car kit construction returning to our shores! -Andy Carlson Ojai CA