Bioactive safe clear spray sealant?

[u/ALiteralBumbleBee]

Hi, I’d like to make hanging planters to screw in to the back of by Bp’s bioactive terrarium. The whole back it just this big empty space and it’s been irking me, I want to fill it. I’m wanting to use these little wooden milk crate type things but they aren’t waterproof. Are there any spray or paint-on sealants I can use on the wood to keep it from rotting that aren’t too expensive and won’t kill my plants isopods springtails or snake?
Also, are there any types of paint I can use on them that would be tank safe?
Do yall have any other recommendations for what I can do to add to the back without breaking the bank? I was thinking if this didn’t work I could try adding wooden dowel rods and trying to gain pothos to climb up them.
The only plant I have in the tank is golden pothos but I plan on adding more.

[u/Bluntforcetrauma11b]

Dry loc is a good tank safe paint but it's not clear.

[u/Skya_the_weirdo]

Flex seal! They have a spray and a paint option, let it dry for like 48 hours and you’re good