I went to WalMart and found, in the automotive section, a pack of 2 14-inch LED strips that shine sideways out of the edge, not out of the front. Pilot brand, "LED Phantom-Lite". They are cuttable if they are too long. I cut off one 3 LED section to place behind my hotend, and put the rest of the strip on the back of the frame shining down onto the print surface, and wired it up like OME did. It works very well, with no extra wood needing to be added. Stick them on a vertical surface, and they'll shine down (or up).

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