NanoLineLock

I use a fair amount of 2mm elastic in DIY gear, for snugging down shorts, cuffs, hoods, etc. Reliable line locks for that size are hard to find. This one is small, light, and foolproof. No springs to break, a single piece, and simple to print. Run the line as shown and it will slide with gentle pulling in either direction. To lock, pull the exiting line into the keyhole loop.