Andy comments

When my foam filter became unuseable, I took one of the one dollar
20X25 fiberglass air condx filters and wrapped it around the dohickey
a couple times, and secured it with a piece of wire.
Seems to work OK, and now I have a use for used air condx filters.

And they are easily removed and washed......

In a later version, I slip one of the wife's old nylon panty hose
legs over the fiberglass and secure it...... Also works OK.....

Andy in Eureka, Texas PE