I was looking for a rail to mount a led light strip on, so it would light up the wall, but not blind you. The only one I could find on here mounted the led strip on an angle, but I wanted one that would have the leds shine straight down.

Used a triangular shape to cover the led strip and stopping it from blinding you, while still looking quite nicely under the shelf.

Includes a "hook" to hold the connector in place, so the weight of the cable does not pull off the led strip over time.
Includes 4.5mm screwholes. 3 per section. This might be (actually is) a bit overkill, but use as many as you want.
Fits up to 14mm wide led strips.

Sections slide into eachother so they should line up perfectly.
Print one left and one right section, plus as many middle sections as you need. Each section is 19cm when connected together. I may make some different section lengths in the future. Designed this for a 190cm Ikea Lack wall shelf.

The triangles on the outer sides are closed off. On the middle section I left them open.
You could open the outer sides as well, so you can run some cables through them!

I also included a little test section, so you can test it without the need of printing the whole 19cm. I used it to see if the sections would actually slide together.

Printing:
0.2mm layers. No supports needed, but some decent bridging may be required or the connecting pieces may not fit well enough.

*Update 1, 2-4-2022

• Changed and reuploaded all files so they oriented the correct way. No rotating required in
  the slicer.
• Added 160mm and 215mm long versions.
• Added flat and downward corner pieces. Use superglue to glue the connectingpieces to
  the inside of the triangle of a mounting profile.
• Added special mounting profiles without the connector and with open triangles, to be compatible with the corner pieces.