DIY ways to close Biocube False Wall?

[Ocean’s Piece]

Hi,

I have had my Biocube 32 running for around 2 months now and I have just started adding snails to clean up some of the algae, diatoms, etc. As some may know, when the hood closes, the wall doesn't have a seal against the top of the inside of the hood and leaves a 1/2" gap, creating an opportunity for snails, fish, etc. to get in the back chambers of the Biocube. I have had one snail get in the back in chamber 3 with the pump so far, and it was a pain to get him out, to say the least. I know there is a product for this, the fish saver from inTank, but it is also $24 which is beyond my budget for a small piece of plastic. Does anyone know of any cheap DIY items that I can use to close this gap?

Thanks.

 

[Ocean’s Piece]

Anyone that doesn’t have any experience with the biocube, is there any cheap plastics, materials, household items, or any thing you can think of that I could use?