I don't have much feel for the cost of castings... what ballpark does "minimal" fall into here... $500? $1000? more? less?
IIRC, Shapeways now offers printing in casting-compatible waxes, but I don't have a clear idea of the costs or the resolution.
Ed
Startup costs for me would just be the cost of the RP model and paying my local jewelry store/rock shop for casting a medium cannister full o' dummy couplers. I could take the time to take measurements and do the 3D model, which wouldn't cost me anything but time, then send the 3D model to an RP firm that uses the Perfactory process, which includes (on certain machines) the high resolution, hard, heat resistant material specifically formulated for making molds for injecting wax masters, which would allow me to make the vulcanized rubber molds. I've got the uncured rubber, I've got the vulcanizing press, I've got the mold frames, I've got the wax injector and accompanying compressor, so that three grand or so worth of mold vulcanizing and wax injecting equipment I'd need just to do molds and inject them, I've already purchased years ago.
So...the difficult part of the 3D model would be the compound curves on the coupler bodies, but the knuckle and shaft would be very easy. Mounting these to cars would require several different coupler pockets for different cars and locomotives, which I assume would be etched like yours, which are excellent.
These would be one-piece and only functional using the old 0-5-0 method.
After I got the RP models and then got the vulcanized rubber molds finished (probably four molds), with eight to twelve cavities in each mold, I'd inject several hundred (eight to twelve per sprue) and take them down to my local jewelry/rock shop along with my pelletized casting brass and let the casting guy there tree them up and make a test cast...which costs me 20 bucks.
All in all, not a big investment...probably less than 300 bucks...maybe a LOT less, since I don't know how much a Perfactory process RP model is going to cost me using the correct material for making vulcanized rubber molds.
One thing for sure, these will be easy to investment cast since they're not composed of a lot of fine, skinny details and the wax molds should be very durable since there are no really fine, long voids to precisely cut and register.
The more I write about this, the more I think maybe I'll take this on this year. If I do, I'll start the project here and get expert advice as to mounting protocols, but I think it should be pretty simple, mainly just multiple hole locations on the coupler shaft, which could be trimmed to the right length by the installer.
FUN!
