I liked the idea of the LED Light Bar by SmokyJoe but found that the adhesive on the LED lights would not stick and the lights would fall down. I decided to take SmokyJoe's original idea and expand on it by adding a sliding profile to hold the LEDs in. I did design this from scratch using Fusion360.
There are 2 parts for each width, A strip that goes all the way across and one with "_Wire" at the end. The one with 'wire' has a small indentation for the wires that connect to the end to power the LEDs. Therefore, I recommend that you print one of each if you are using and Ender 3.
I have a download for each 8mm wide LED strips and 10mm wide with each length being 165.1mm (6.5in). If you need a different width or length, don't hesitate to ask in the comments. I learned about perimeters in F360 and it literally takes me 4 clicks and 2 keystrokes to change them.
These are the LEDs I used with the 8mm profile: (Amazon associates link)
LED Lights - 6k Cool white, non-waterproof, 2835
This is a guide of how I added LEDs to my Ender 3: Adding LED Lights to my Ender 3
I printed mine vertically with no supports. Risky, I know.
If you want to print them horizontal, you will need supports. I would print it with the part that goes in to the 2020 extrusion touching the build plate.