Cord Lock Bead for small elastic straps (on face masks, etc.)

thingiverse

This is a simple one-piece bead or cord lock, primarily designed for taking up some slack on the elastic ear-loops on face masks. They work great with the 5mm-wide flat elastic loops on my current main mask and should also work with any sort of similar mask-elastic. This design has a 3mm-diameter hole at one end, and another 3mm-diameter restriction in the middle, to give fairly good friction against the elastic without it being excessively tight. It works great for me, holding properly in place but able to be adjusted without feeling like I'm damaging the elastic. I suggest putting these on the elastic such that the loose part (the slack) is sticking out through the larger (top) opening, with the small-hole end pointing towards the mask. I do that by passing a thread through the large-hole end, loop that thread through the elastic and then back through the bead. Hold both ends of the thread and gently pull to drag the elastic through. The thread-path through the bead is tapered in both directions so thread should move through easily. It prints to 10mm tall, 6.6mm diameter across the outer ribs and uses very little filament (PrusaSlicer estimates 0.22m of 1.75mm filament, about 0.65 grams, for a set of four!). Ideal if you have some scraps left over at the end of older spools which aren't enough to do "anything much at all" with but you can't quite bring yourself to throw away. Or, if you have some short filament samples in assorted colours, you could colour-match these to your mask - just like I did. If you want to inspect, or maybe tweak the dimensions (to make the friction-hole size a bit smaller or larger, if needed for your particular needs), both a Fusion360 F3D archive and STEP file are included along with the STL.