It has a 10mm hole most of the way down and a countersink to take a ~5mm wood screw.
A 2mm self adhesive felt pad covers the screw hole and acts as a shock absorber.
It has a rim around the bottom to prevent it rocking if the base warps or the wall is not flat. To support the bottom of the hole there is a one layer membrane: -
I removed it with a 5mm drill: -
I was quite proud of it but my wife had something more like this in mind: -
I can't print chrome yet, so I will have to go out and buy one, and it has three screws which have to be drilled through the tiles into the wall.
The files are on Thingiverse if you prefer function over form.
