Here's a site that has a wide range of 3D details in a variety of scales. Mostly 1:35 or larger, but some railroad stuff is 1:87 and smaller.
They have large a variety of rivets, nuts, bolts pipe fittings, military pieces, animals...basically a lot of stuff and they look good.
https://emp3d.eu/
I looked at an HO scale tank. The print quality looks outstanding, probably better than injection molding. Most impressive. -- Russ
Had a look too, some VERY useful stuff and, as you say, it seems high quality.
Les