I needed something to screw into an Edison light fitting and provide a large flange, so I took FluidDoc's excellent model as a starting point and used TinkerCAD to replace the original "finger plate" with an octagonal flange instead.

FluidDoc designed the original to fit into a US E26 socket but I can confirm that it also works perfectly well with the European equivalent, the E27.

I echo FluidDoc's statement that this is not to be used on a live high voltage AC circuit!

The reason for needing it was to make a concrete lamp out of IKEA parts: https://www.instructables.com/id/Easy-Concrete-Lamp-From-IKEA-Parts/