The endcaps often break, catch on things and get lost.

It took me five attempts to get the size exactly right - too large and they catch on things. I hope it suits other people's blinds.

I've included a .step file so you can amend if necessary.

Inserting the cap into the end needs little wiggle, but this is intentional to ensure it stays in place.

Printed on a Mk3S+, 0.4 nozzle, 0.2 layers in PLA.