A very simple drainer for a standard UK plug hole size of 1½" (37.5mm) with a ½" wide brim.
06/02/2024 UPDATE: I've created a v2 with larger holes as I found that the original size holes quickly filled with soap gunk!
I've included the FreeCad file should you want to modify it to a different size, but please don't judge as I find FreeCad exceptionally frustrating and I'm sure it's not a good example of how to do things 😉. FreeCad is quite possibly the worst bit of software I have ever encountered!