This instructable is my first one using a cad (computer aided design) software and 3-D printing! The rings are surprisingly simple and fast to design and make - it only took an hour to print all 3 of the rings with a slower speed (for better quality). The design on Tinkercad also only took me under 5 minutes to design and make without a single thought on what these were going to look like (I improvised a bit). I was inspired to make these for the made with math competition, and for a never ending collection of 3-D printed objects. Anyway, I hope you enjoy reading and making the rings!

Supplies

3-D printer with some filament (I used PLA, but ABS is fine as well)

Acrylic paint and a paintbrush

Tinkercad

Step 1: Designing the Rings

Open Tinkercad and make a new design. Take a cylinder from the basic blocks and bump the sides up to max (64 - this just makes the cylinder look more neat and round when it prints). Next, make the side lengths 33.60 mm (or however big the circumference of your finger/napkin is) and the height 7mm. The sizing for this ring is for a napkin, but I just scaled the ring down by 30% or so when I sliced it in Cura. Next, take a twisted polygon from page 7 of the shape generator (it is not in the featured column). Make the number of points on that 9 (or whatever you like the best - it is a matter of opinion) and change the side lengths to 40mm and the height to be 7mm. Finally, select the two shapes and align them using the middle dot on both sides (basically put the cylinder inside of the twisted polygon). After you have done that, group the shapes and export your ring to Cura or another slicing software.

Step 2: Slicing, Printing and Painting the Rings

Here are my some of my Cura settings:

Infill: 100%

Quality: 0.1mm

Speed: 40mm/s (this can be raised or lowered)

Adhesion: Brim

Support: None

If you want to make the rings smaller (the ring size that comes into Cura will be that of the blue ring) just scale the ring down by 30%. After the rings have finished printing, start painting them with some acrylic paint (I chose blue and gold) and then you can dry them with a hairdryer if you want to dry them faster. I used a standard glossy blue and gold, but you could do any colour you like.

Step 3: You Are Finished!

After you have finished painting the rings, you are going to want to let them dry before you wear them because the paint could still come off. If you liked this instructable please let me know by clicking the heart button, and if you want to see more like this one, then please let me know in the comments section - I always like a new challenge! Thanks for reading and I hope you found this helpful.