Cool!! I could buy like a thousand or so legos from ebay for a few minibogs then fuse them together using a multipurpose plastic cement that will melt them then let it gass off for a few days. Tbhat would make it all water proof
The cement would be multipurpose piping abs,cvc and pvc cement.
The stuff stinks like well it is nasty stuff but a if you build it with that stuf dbetween each briock you could make lego bogs. Then I'd wait 2 weeks for it to ir out in the garage.
You could always try using aquarium grade black silicone sealant. It's non-toxic, waterproof, and would not look nasty over time like the clear stuff. (plus it only smells like vinegar.... which i guess is pretty nasty but I imagine not as toxic as the cement stuff)
Very cool idea btw . Thanks for sharing =).
Next step...lego lowland nep terrarium??