4 mm rivet - locking pin

4 mm self-locking pins 

I've originally designed these to lock corrugated plastic (yard signs) but they can be used for any other application. 

The last time I printed them was on an Ender3 with 0.28mm layer height and I found that the layers lines helped with the grip. Please let me know if the grip is not as good with these settings and I will make another settings profile. 

The rivets held surprisingly well last time I tried them.

Hope these can be useful to whatever project you're working on!