I recently added some leds under my headlights with a dedicated controller.  The strip I got from amazon was too long, so it had to be cut.  I used this and some clear silicone to cap off and seal the end of the led strip that got cut. Photo provided for reference.

The picture used in my photo is printed at .08mm layer height, but other layer heights will be fine, I just really didn't want to see the layer lines.

The strip can be found here: https://a.co/d/ap1GVTo 

Not sure if this will work with other strips, but it does work with the one in the link above.  I will post dimensions and photos as well so you can check before you download and see if it matches closely to yours.