I almost exclusively print functional things so here's my list of things I've designed or printed:

• Tubular key to bypass paying for laundry
• Furniture leg extensions on almost all my furniture to give minimum 4" clearance for the robovac
• Custom mounting bracket / spacer for mounting road sign to the wall with command strips
• Tapestry mounting shim to clamp tapestry in binder clips to hang on the wall without ripping the tapestry
• Rubber band powered sandal holders that stick to the wall and clamp onto sandals which can be used without using your hands / while holding something (I needed to keep my basement sandals from being eaten by my old robovac and I needed to be able to put them on and put them back without needing to put down anything heavy I'm taking to/from the basement, and the space required it to be flat against the wall)
• Replacement shelf pegs for bathroom shelves which are normally only sold in 20 packs for >5$ when I only needed 1, the print cost like 1c instead
• Replacement D-slotted electrical box key since the one that came with the box broke
• Backyard lamp holder that attaches to the fence pole and provides a loop to hang a lamp
• Replacement side panel clip for my PC case which came with 1 broken - manufacturer doesn't sell replacements
• Custom piece for 2 sectional couch legs to slot into which keeps the 2 halves of my couch from sliding apart causing someone to fall in between onto the floor

Some of this could have been bought online but having a 3D printer really reveals how overpriced plastic stuff is. I rarely print something that costs me more than a few dollars in filament - and that's if it's a very large object, it's easily less than the shipping cost of an equivalent item alone, and small things can often only be found in large packs online while usually costing only a couple cents to print. And plenty of the stuff I print benefits from being able to be made custom and to the exact dimensions I need, for example the furniture leg extensions I made fit perfectly on the furniture legs and raise them up exactly as high as they need to be for my robovac to go under, not a centimeter more. A whiteboard marker caddy I made holds the exact number of markers I have / want to have and attaches under a light switch wall plate which I designed in order to avoid needing to attach it with command strips or screws (it gets clamped between the wall plate and the wall by the existing light switch screws). The first item I listed, the tubular key, was printed with the exact bitting needed for the lock (layer height of 0.05mm is enough vertical resolution for the key to work).

I dunno about other guy, but I came here to say 3d printer.

I've printed small plastic parts to fix the flush mechanism of a toilet for pennies. I've printed little utility items like hangers for parts to paint. Holders for dnd minis to make painting them easier. Storage boxes to organize small parts for various other hobbies. Giant realistic cock and balls turned into a trophy. Replacement parts for board games that have been lost or broken over the years. Custom dice towers and dice boxes for dnd dice sets. Etc.

The ability to see a need, take some measurements, and spend a few minutes in a cad software to have a replacement part that you otherwise can't find (or can't find by itself) is honestly amazing.

The simplest thing I printed is the one I'm most happy about, I had a power bar dangling beside my bed for all my chargers and I printed 2 small clips and it holds it great.

I printed bookcase supports, an air filter and tons of custom boxes for electronics. I learned the basics of SolidWorks so I could design stuff for my printer (ender 3 S1)

I've recently been working on a cube tomato project. I have those models up on my Printables account. I'm planning on uploading more useful stuff I print up.

https://www.printables.com/model/573244-cube-tomato-mold-v3

Geometric frames of the same size and thickness to make a 3 tiered windchime from upcycled glass!

I use my printer for making replacement parts for things, and for making simple stuff I need like tools, and also for prototyping.

An example: I used to have this motorcycle. The mount for the taillight broke. A new one was $100, and it would break again the same way. So I measured the socket in the fender, measured the bolt holes, and designed my own, which worked flawlessly the rest of the time I had the bike.

Off the top of my head I made a ssd>hdd mounting adapter for my pc. A replacement clip to fix my headphones when they broke, a latch for a pet carrier, replacement part to fix a lamp to it's base, and a mount for a bearing my mom used to make a lazy Suzan.