Another (now pretty routine) LED Christmas light repair. The pretty blue snowflake LEDs that live around the living room mirror were dead. I took the string down, pulled the bulbs, tested each (with the LED tester on the front edge of the bench) ’til I found the bad one, replaced the LED and it’s done. It was the usual 3mm LED and a diffuser that snaps into the socket. The LED fits up inside a hole in the middle of the diffuser.
The only mildly interesting bit was that the 3mm blue LEDs I had have a sort of collar around the bottom. I had to hack that off with some flush cutters in order for it to fit up into the diffuser. Quick and painless.
Much more interesting was being reminded (as I took the string down) of the clips I used to put the lights around the mirror. I cut some strips of the very nice clear plastic used in all those annoying clamshell packages. (I can barely 
stand to throw the stuff away, and have a nice stash for just such occasions.) Bending a loop of it to fit around the wire and slipping the rest behind the mirror (or into the window frame or where ever) provides a fairly secure, almost invisible mounting clip. It’s easy to tweak for fatter or skinnier openings, and it’s free! (Well, assuming that you keep a stash on hand. You do keep your old clamshell packaging, don’t you?)
Good Idea.
This is a good time to stock up on LEDs. I got a battery powered string at Walgreens for $2.49 and harvested 15 white LEDs and a two AA battery holder with switch.