Lamp Shade Mounting Hole Reducer

Lamp shades for table and standing lamps come with a hole suited for european style lamp holders - approximately 40mm.  You can get adapters to reduce this to the size of the B22 standard - approximately 28mm. The problem is that these adapters have a 2.5mm slot around their circumference, and the thickness of the metal ring on the shade is only 1mm. This means that when fitted the shades wobble around and can not be tighted.

My adapters are in two parts so they screw firmly down on the shades metal ring.

There are two set of STL files. One for plastic lamp holders, and one for metal lamp holders, as the metal lamp holders have a slightly smaller diameter.