My house has a timber deck out back with some small LED deck lights. Some of the lights have failed or broken, and they are quite expensive to replace and painful to fix. I designed and printed a replacement part using translucent ABS. It is sized to fit in the same 20mm hole, and uses 3 x Blue LEDs and a 100ohm resistor is series for a 12VDC supply. I coated the finished product with outdoor clear varnish which hopefully will provide some UV protection.

The third photo shows the printed version vs the original (which has the metal surround).

The design on the light is in the OpenSCAD file attached. There are 3 holes sized for a snug fit of standard 5mm LEDs. It's better to assemble and solder up the LEDs separately (I used a cut up test print as a template/holder). Then they can be carefully pushed in place and the end filled with silicon sealant.

The design on the light is in the OpenSCAD file attached. There are 3 holes sized for a snug fit of standard 5mm LEDs. It's better to assemble and solder up the LEDs separately (I used a cut up test print as a template/holder). Then they can be carefully pushed in place and the end filled with silicon sealant.

The OpenSCAD design can be tailored for different sizes and profiles. The "burrs" help keep the light in the timber hole without having to use glue.

I printed using clear ABS on a Migbot Reprap with 1.2 walls and 0.1mm layer height. I used a brim for adhesion and cleaned up the edges with a dremel tool.

The deck lights go into a 20mm diameter hole in the timber decking - the wiring is hidden underneath. A purist may want to indent the top square by a millimeter or so. I haven't bothered since the lights are placed near the walls (not in an area where someone will kick them).