Moin!
That really looks great, how sturdy are these nylon printed parts? I got no experience in 3D-printing and it's about time, I guess.
And yes, I do that metal stuff by myself, using my 3-axis CNC mill and a small conventional turning lathe. My workshop still lacks a 3D printer so far.
So far, I've not made any parts that would really load up stress on the material.
I've mostly been using 3 mm wall thickness, which felt really strong.
In this picture ...
... the clamp of the big sight mounting for the Kowa has 3 mm thickness. You can easily bend the ends together without much force, but the material springs back when you release it.
The small white rail (which goes on a hotshoe) experimentally took a 450 g target scope without sagging. That was just for fun, normally it only takes the red dot sight, but I was pleased it held up so well.
Thin stuff like the base ring of the accessory thread sight mounting is a bit more of a concern, thus my attempt to bring some load on higher walls (which get in the way of screwing on the cover ring).
The advantage of 3D printing is that you can do arbitrary shapes, and it's all produced in one go. I'd guess CNC-milling all the slots in the rail would have been quite time-consuming ... the 3D printer just adds stuff whereever it's needed, regardless of complexity.
I don't actually have a 3D printer, but use online services for printing. The black parts in the picture are from shapeways.com, the white rail is from meltwerk.com. Meltwerk often is cheaper, but the prints from Shapeways seem to be a bit more refined. Shapeways also offers printing in other materials, even steel, but that tends to be more expensive.
(I just checked a somewhat slimmer version of the accessory-thread sight adapter, and Shapeways say in steel it's just over 50 EUR.)
The laser-sintered stuff you get from the service providers is pretty homogenous. The exact printing process seems to require a lot more attention if you're using a typical consumer 3D PLA printer, not only because you have to fiddle with the process parameters until it all works, but also because depending on the intended purpose of the part, you'll want to have the layers oriented in a certain way so they bear the load, or can be printed most accurately, etc.
I don't think a consumer 3D printer can beat a personal CNC mill, but I guess it will be a nice addition since it has a quite different set of strengths
In fact, I read that some people prefer to buy the CNC mill first, and then use it to build a 3D printer that's way better than what you can buy in the store!
However, I'm sure a CNC mill requires a lot of knowledge about metal working, so I'm not tempted to buy one right away - though looking at your beautiful mounting, I'm almost tempted ;-)
Regards,
Henning