I wonder if anyone makes replacement grilles for box #fans that:

1. hold an #HVAC #filter on the intake side, and
2. shroud the corners of the output side.

This would be awfully convenient for #AirPurification

A prefab frame for a #CorsiRosenthalBox would also be interesting.

#fan #AirFilter

@argv_minus_one do you mean like a Corsi-Rosenthal box, only for the one side?