It’s downright amazing what you can find if you look hard enough. There is someone out there who has the basic printings, courtesy of Shapeways, to make an HO scale Reading T-1 4-8-4 if you’re so inclined. There’s even a gearbox cover printing available, although you’ll have to supply your own gears, not to mention motor, wheels, rods, valve gear, etc. All this for the grand total of $567.22 without shipping. My recommendation for drivers is Greenway. At $20/ea, a set of appropriate 70” drivers will set you back $80, again without shipping. Greenway can also supply other wheels, but I haven’t priced them out. My estimate of the total cost of this project is around $875-900 if you want DCC and sound and somewhere between $750-775 if you don’t. Of course, you could always just spring for BLI’s latest offering, which is substantially cheaper even at MSRP, but where’s the fun in that?

https://www.shapeways.com/shops/tim-s-3d-prints

Before any accusations start to fly, let me make some things clear. I’m not questioning the guy’s pricing. Nor do I think that he’s greedily trying to empty your wallet to enrich himself. Just from what I can make out from the pics, the stuff the gentleman offers looks pretty good. Actually, that chassis might make a good start toward a NC&StL J-3, a Cotton Belt L-1/SP GS-8 or a D&RGW M-64. I’m also not calling into question the whole “crowd sourced” steam locomotive idea, although I would opine that the concept is best reserved for producing items that either don’t stand a snowball’s chance in hell of ever being commercially produced (e.g. Rene Gourley’s 4-4-0, Adrian Gunzburg’s Western Australian U class 4-6-2) or are at least unlikely to be commercially produced (e.g. any locomotive used by the Maine Central other than its 6 USRA light Mikes).

Well, anyway, the challenge is out there for anybody who wants to use Shapeways available parts to build a 70” driver 4-8-4. It doesn’t have to be a Reading T-1. Other options were mentioned above.

As usual, writing things down leads to other ideas. Rather than a crowd sourced steam locomotive, how about some printed parts like cabs, tenders (like, oh, I don’t know, maybe an SP 90R-1 or a 73SC-1). Some Harriman style cylinders for 2-8-0’s/4-6-0’s would be nice. It would make converting a  Bachmann 2-8-0 into an SP C-8/9/10 approach “piece of cake” mode. I might even be motivated to part with some cash for a 3D printed version of SP’s parlor car “Oliver Millett”.

I didn’t want to step in the “crowd sourced” thread, which is why I posted this (partially) tongue-in-cheek challenge. However, it does occur to me that available commercial chassis might be a reasonable starting point for something else. For instance, the USRA light 4-6-2 chassis would be a reasonable starting point for an NKP or MEC 4-6-4 or even to cobble together a  model of MEC 470, currently undergoing restoration.  https://m.facebook.com/MCSL470Restore/   

The Reading T-1 chassis options were mentioned earlier. It also might be nice if there were a Harriman boiler and cab to fit on the USRA Mikado chassis. Then there’s the NYC/NKP H-5, which has only been done in brass. Both the Harriman and H-5 boilers were essentially cylindrical, IIRC. The real question is how close in diameter were the two? I can supply dimensions from the Harriman, if someone else has info on the H-5. If they’re fairly close, it would be a twofer, and only different cabs would be needed.