Yes, it's another LED strip holder. I know there's a lot of these on Thingiverse but I couldn't find one to fit my preference of having more than one strip over the bed. Wanting to do timelapses, I thought multiple strips overhanging the bed would provide better lighting, and in my testing that seems to be the case.
The advantage of my design (in my humble opinion!) is that the bracket attaches easily to the top rail while holding the LED strip further out than other top rail solutions. This mitigates the hot end assembly's interference with even lighting of the bed.
Further, the extension arm, which snaps into the end of the bracket, can be used to attach one or more additional strips as needed. For the Ender 3, a second strip will end up above the edge of the bed when it's fully forward.
To print, you will need 2 (or more!) LED Brackets, and at least one LED Strip piece. How many you need is up to you. By default the LED Strip is 25cm long, but can easily be scaled down (or up) according to the length of your LED strips.
LED Strip pieces are sized to comfortably fit a 10mm wide strip and should thus fit smaller strips if needed.
The LED Strip thing is oriented correctly for printing, but you may want to add a brim or print it smaller if your printer can't handle the full height. Mine struggles as it approaches the 20cm mark. LED Strip Connectors can be printed to join shorter pieces together if they don't span the gaps between brackets. You can see an example in my provided pictures.
All pieces should slide or snap together without needing glue, though some double sided tape may be useful to hold strips to brackets and connectors to strips. Hot glue at the joints should also work well, if necessary.
25% (for bracket and arm, 0% for strips and connectors))
Depending on the tolerances of your printer, all pieces should snap or slide together fairly easily. The hardest parts are likely to be snapping an arm into a bracket. That fit is tight by design, but if they won't fit together at all they should be easily trimmed or sanded to size. If they're somehow too loose, squeeze some hot glue or other adhesive into the joint.
The LED Strips are designed to be printed upwards on the print bed, no matter how mad that looks. If you need it shorter, scale it down on the Z axis ONLY. This can also be done on the connectors, if you want a longer or shorter piece. You could theoretically print connectors the full width of the bracket gaps if you wanted, but that's probably not necessary.
Printing this in PLA is probably fine. The LED strips I've used were intended for TV back/bias lighting and are fine to run 24/7 without overheating. If you have particularly powerful or hot-running LEDs you may want to do it in PET-G, ABS or other higher temperature material.