Replacement cover for WAIT 5000 12 gallon flow-through furnace humidifier. Part seems either discontinued or out of stock everywhere.

You'll need a good sized printer - see photo for orientation which allowed me to do it in a single print. Top bracket hole intentionally doesn't go all the way through to avoid needing to print a support branch - drill out with an 11/64 bit. Uses about 620g of filament.

Printed here in PLA, but given that the glassing point ~60-80°C of PLA is close to the operating temperature it has sagged a little over time - I'd recommend printing this in ABS.