Pretty simple - just a plug for a bathroom sink. You can tell it the diameter of the hole, and it will create an angled cylinder passing through that measure, with a cap to prevent it falling in, and optionally a handle for easy removal and/or perforations to allow water flow.

Measure your plug-hole's diameter, set this as the od in the OpenSCAD file, or pass in half that to the drainplug() module command.

The other parameters are:

depth - this is just the depth of the plug itself, the bit meant to fit into the hole to seal it.

variance - this will be added to and subtracted from the radius to create the angled; set to 0 to get a flat vertical cylinder.

perforations - four options currently; 0 for no perforations (i.e. a proper plug to allow filling the basin), 1 for cylindrical perforations, 2 for square perforations, and 3 for a honeycomb pattern of hexagonal perforations.

handle - three options currently; 0 for no handle (the cap sits above the hole intentionally, to make it too large to fall in, and is not hard to grasp), 1 for a round handle on a stick which requires support and bridging to print, or 2 for a simpler inverted cone that should print without support, but maybe not look as nice.

fineness - this just gets passed in as the $fn parameter to the various cylinders

For the solid plug, if you want a better seal, just paint the bottom portion with rubber cement to form a makeshift o-ring equivalent.

(Though you can see a standard plug in the action picture below - the reason I needed this is that the support arm it is supposed to link to, which allows it to be raised and lowered, has rusted away, so it always seats fully, and is difficult to remove.)