This thing is a replacement part for 3rd gen Subaru Impreza cup holders. It may fit other Subaru models from that same period. It helps center a standard diameter beverage can in the cup holder so it doesn't slide around. It also collects condensation and leaked drink.
It probably could use an extruded honeycomb pattern to give liquid a place to run off to...
cup-holder-insert-1.stl | 403.2KB |