I'm not sure ever posted here, hmm!
I dont know if you've furthered your project any, but I thought I'd throw this in the mix.
I did a divider once with plexiglass and I used suction cups to hold it in place. It worked great but the female still managed to slip past the edge til she got bigger. lol
It might have been 3/16 inch gap on either side. (upon that thought, I should have cut the divets deeper to set the cups in closer.)
so, this was my result.. http://pics.livejournal.com/lanternlife/pic/0000daz6/g1
if you want to, look in that gallery you can see more pics with it in the tank.
Lets see, erm my point.. I was thinking that I saw a design once, which had a plexi frame that had the plastic canvas glued onto it. but I cant remember how they attached the frame to the tank. I cant find that link, of course! ;/
anyway, hope your project works out! :}