I bought this LED bar -→ https://www.aliexpress.com/item/1005005787406587.html?spm=a2g0o.order_list.order_list_main.83.557018021ViiJB.
This LED bar can actually go straight into the cavity of the 2020 extrusion, but that would make it pointing straight forward. I wanted it to point 45 degrees downward to give it a better lighting, but couldn't find a good one, so I designed one.
Printed 2 just to hold both end, but feel free to print 3 for the middle if you think you need one for bigger printer.
I printed with PETG to give it a bit more flex for the clip to go on the extrusion
The author marked this model as their own original creation.