I 3D scanned my drill with an aircraft-length bit installed. In CAD I set an axis thru the center of the bit and put a plane normal to the axis at the back and extruded back to the outer surface of the drill.  Adhered a bubble level to the back, now my drill tells me when it's level within 0.6°. 

Mini-project for something else I'm still working on.

Designed & 3D printed a hinged box with epoxied-in glass panels to store patches on my workbench. I reamed the holes for the hinge to be a tight fit around the pin, which is a round standoff with two shoulder screws on either end. 

Built around a 3' thin carbon fiber tube. Threaded insert epoxied-in with a swivel stud tie point on one end, Buna-N foam grip on the other with a 6" tungsten rod epoxied in the handle for counterbalance. It feels weightless to swing around, the center of gravity is right at the top of the handle.

Heavy solid-brass deck-mount dispensers converted to fit a thick glass jar.  I used an ultrasonic knife to cut the old plastic pump out of the cap, and epoxied the threaded remainder into the brass deck mount.

Lots of PVA glue and water-activated packing tape.

The sponge holder base is solid polished brass 5"Ø x ½" w/ adhesive neoprene on the bottom. I 3D printed an alignment jig to hold the shaft perfectly vertical while I epoxied it into a hole in the base. Shaft is carbon fiber rod. Shelves are 3d printed PLA, printed & chased threads to accept large SHCS's to support against the carbon shaft. Inserts are standard 8oz deli-style containers, easy to clean/replace.

I mounted a red dot sight to a bug-a-salt. A single pump builds compressed air which shoots out table salt for killing flies and small insects.  It's hard to aim when they're flying, but the red dot helps.

Built around sawhorse brackets, some 2x4s, and a 2x6. 1/2" hardware, 3/8 chain, bolt held with a castle nut. Chain offset on washers to produce downward angle, deflecting debris to the ground.

CAD designed and 3D printed, now I can actually find what I'm looking for.

18" cling film core tube wrapped with sisal rope. 3D printed inserts with screw thread inserts glued into the ends. Wheels screw on and fit a large silicone o-ring as a tire. (cat toy)

I made about 2 dozen dice for my fiancée as a cast gift for a show she was in.  3D printed out of PLA with multi-color printing for the logo inlay ("Save the Game") designed in the slicer. I added a touch of high-gloss black paint to each of the number indents and sanded down to #800 on all sides.

I remixed a Bambu AMS dessicant holder w/ humidity sensor to have the mounting at a 45° angle (the angle of the LCD was illegible normally, which was perpendicular to the outer surface). I also made a quick desktop holder with a sitting-down angle and a standing-up angle.

A quick 3D print to store pre-cut pills for our cat sitters when we go on trips (tiny cats need tiny doses, pills only come so small).  These are original containers for the same pills from previous refills for better environmental storage.