I designed this LED light mount and holder for Ender 3 printer so I can use three strip LED light each strip is (9 LED's) as in photos.
I used a 12v three strip (9 LED's in each strip) so max current will be very low about (500mAh for all the 3 strips) so you may use any small cheap 12v 500mAh adapter.
If you like to use your printer power supply make sure to use DC to DC Buck Converter and adjust the output to 12v for the LED strips.
I am using my printer power with a Buck Converter.
I soldered the 3 strips together and used a double face tap to attache it to the 3d printed mount.
I printed with PETG but you can use PLA or any hard material.
Easy to mount in the printer, just slide it in from the side of the top part as in photos.
Any PETG or PLA
You may need to use brim for the small end area of the mount that is touching the bed.
You may need to add some paper glue on the bed before printing on the area where the small end part of the mount is touching it.
Design and modeling