Decided to replace the two 2½" round red roof marker/clearance lights
on my Burro
with LEDs. Wasn't necessary but curiosity about this new technology got to me. Two inch round LEDs came, from an ebay source in Michigan. So I see the fixture components are sealed-imbedded in a cake of resin, like a neat plastic pie.
The price was right but now I know why they only cost $2.35 each. They have a plug-in, twist-on bayonette type mount, but came with no mounting grommet/base. I wanted to flush mount the fixtures using the same holes as the old fixtures.
After a day of digestion it ocurred to me I could make my own mount. I soldered wires into the plug-in. Then made a template, and shaped/glued up white plastic into being the twist-on mount. The plastic cut easily with snips and with a utility razor knife. It needed two 2" round plastic disks per fixture. They are glued together with Loctite glue. The inner one had a tapered bayonette mount shape and the outer one added the thickness necessary to clear the mount, alongside with added rubber washer made from an old inner tube.
Hey, it works.