For my last project (https://www.thingiverse.com/thing:2754147) I used a short piece of filament for the pins in the hinges. To keep them in, I used a hot air gun to heat up the blade of a knife. Then, I pressed the side of the blade to the end of the filament and melted it until the diameter was about 50% larger than the original O.D. This was functional, but I didn't like the flat end and the sharp edge that it made.
So, I decided to make a tool who's sole purpose is to form a button, or rivet head, on the end of 1.75mm filament. I started with a long #10-32 bolt -- the kind with the blank shoulder area. Typically, screws longer than 2" have 1" of threads and the rest is non-threaded shoulder. A #10 screw has a body diameter of 0.188".
I cut off the head and drilled into the blank end with a 0.110" drill, about 0.020" deep. So, the cavity is a cylinder made by the drill that is 0.110" diameter by 0.020" long PLUS the point of the drill. See picture 2.
Then I drilled a 0.161" (#20) hole into the end of a 5/8" diameter wood dowel and screwed the bit into the dowel. I decided to use wood instead of printing a plastic handle because I was afraid it would melt while heating the tool bit.
To make a rivet head, heat the tool bit with a hot air gun. While it's still hot, press on the end of the filament until it fills the cavity. What you end up with is a nicely formed rivet head (picture 3).
BIBO2 Touch Dual Extruder X Laser
I'm not sure this qualifies as a project for Thingiverse, but it's used to help make parts that are 3D printed. However, I will comply if the web master asks me to take it down.