Now I am very curious to see your 3D-printed Marlin firsthand - for several reasons. Three-D Printing is an obvious Next Move for me - BUT, IMHO it is just "Not There" yet, for smaller-scale parts. I fully understand all the excitement with 3D-Printing in general, but - again, my opinion - it has been hyped for modelling virtually across the board, which has in the case of many smaller parts (so far) been ridiculous. Plus, as you suggest, not every idiot with a 3D-Printer can now suddenly make the decent model part you need: there still remains the need for research: to come up with accurate drawings - something still also plaguing me, for the Marlin - PLUS the added labor/cost, now, to get it all into a high-resolution, 3D-CG file.
But what's keeping me from getting into 3D-Printing myself is, first of all, the limited vertical resolution - that is, the layer thickness - which still wildly exceeds the (excellent) horizontal resolution: leaving a striated surface - minute ridges and valleys - running across each part. They have offered tricks like re-melting the surface, to (somewhat) smooth this out - but then you loose the fineness of detail, in all directions: it is an insoulble problem, absent finer print-head technology. And I don't know but that advances in materials might be required, as well.
Speaking of which, the materials are my second problem with 3D-Printing, currently: there seems to be some sort of requirement - I have no idea why - that the materials be quite hard . Which is a Royal Pain in The A** for anyone wanting to customize or modify their parts: a key option, deliberately engineered - for easy conversion between close variants, like the E-1 Tracer and S-2 Tracker, for example - into as many of my parts as possible.
And finally, mass production with 3D-Printing is apparently not cheap - not compared to resin casting, anyway - so that the above improvements, when they arrive, are still likely to jack the costs beyond any reason for switching to 3D. So, there will be yet additional waiting for those to come down, as well.
But - seeing as how all the above will no doubt - eventually - be solved, I continue to watch closely, ergo: send me that 3D Marlin, David - and we'll see just how much better mine (still) is. And who knows but I might also be able to get something(s) helpful to my master off of it, too.
I'll trade you 6 Matty's Models Marlins for it! Just kidding - you're getting those For Free - but I'll send you an eMail, buddy!