SWIM's using tyvek over a lid with four holes.  SWIM's space is too limited to raise the fruiting chamber much higher, but the area is easy to keep clean.

SWIM loves the idea of using water heating to heat the incubation chamber!  SWIM imagines that this would be desirable for a fruiting chamber (monotubs suspended over heated water in a larger tub) as well, but at a lower temp?  This seems like it would be a far more precise way of maintaining proper temperatures, especially in the winter.