I saved a lot of money by printing one of these and could not get it to stay in place easily.

[https://www.printables.com/model/59932-3d-printed-u-channel-for-leds](https://www.printables.com/model/59932-3d-printed-u-channel-for-leds)

So, I designed a small bridge that holds it together.  You can glue it if you want, but the tolerances are small enough that it should just slide right over and hold in place.