On Sat, 14 Mar 2015 22:18:43 +0000 (UTC), John McCoy
wrote:

Dick Snyder wrote in
:

I do not have enough space between the doors to put in a stiffener. I
am going to call my plywood supplier to see if they have any better
ideas. Otherwise I may go with painted hardboard.

This is a bit of a long shot, but if you have a source of
1/16" veneers you could try making up your own plywood.
Put the two inner layers at 45 degrees to the outer layer
(and 90 degrees to each other, of course), and use epoxy
(West System or System Three or similar) to glue it all
together. You'll want to glue it up on something flat,
and have another something flat to put on top together
with a bunch of weights while the glue dries (and plastic
wrap between so you don't glue your panel to it). The
result will be a lot stiffer than any commercial panel.

Otherwise I'd be tempted to go with Gordon's suggestion
of frosted glass.

John
Another thought - try to get "aircraft grade" plywood - 45degree
instead of 90, and all veneers "A" grade.