Just an idea here:  How about using the blue foam that campers use to lay
on at night, they can be cut formed and glued --- maybe.  just a thought.
Malcolm S

Karl wrote:

> Several posts have suggested using weather-stripping.  Don't see how this
> would work, since the flaps are actually flat sheets of foam.
>
> I don't have one in my hand, so measurements are nowhere near accurate, but they
> are approximately 2.5 x 4 inches (about the size of a poker card).  The trick is
> that in cross section, they have a lip, sorta like this ^------------------^  .
> The lip fits around the perimeter of the plastic flap, or more precisely, flap
> halves, since two of them snap together around the spindle, and actually makes
> the seal.
>
> Thanks,
>
> Karl Wolz