I've been keeping reefs for over 20 years, and like most reefers, I've spent a lot of that time rigging up solutions to problems that nobody makes parts for.
About 7 years ago I started 3D printing my own accessories for my mixed reef. Flow directors, light shades, frag holders, mounting brackets, and so on. Whatever I needed that I couldn't find anywhere else.
At some point friends started asking me to make things for their tanks too, and Reefing In 3D kind of grew from there.
Everything in the shop started as something either I, or someone who reached out to me, actually needed. I run a mixed reef, so I know what precision flow and lighting means for a tank, and I design with that in mind. Nothing gets listed until it's been tested in/on an actual reef tank.
If you're looking for something specific that you don't see in the catalog, send me a message. I'm always working on something new, and half my best designs came from someone asking "hey, can you make something that does this?"