I needed a small fish bead to make knitting stitch markers for an upcoming fiber festival. I took a public domain SVG file into Tinkercad, resized it and added a hole. After printing, I threaded it onto a loop of fishing line, added some crimp beads, and voila! 

I printed this at 75% infill to give it weight, but next time I'll probably go 100% infill. These are tiny tiny tiny, at less than 1g of filament per bead. Original size is 18mm x 12mm x 3mm but you can easily resize it as needed.