David F.
David F. thanked K. B. Baldwin's answer
I would like to build a high-quality indoor tabletop fountain. I cannot find a suitable container for the base. I'm looking for a square or rectangle around 12-14 inches on one side that is not breakable and not too deep?

Places like Home Depot and Big LOts sell plastic storage containers in a wide variety of sizes.  They seem durable, as I have crap stored in them in my garage with no ill effects.  And the temps in the garage will go form as high as 101 to a measured low of 30. 

David F.
David F. thanked Firstname Refreshme lastname's answer
I would like to build a high-quality indoor tabletop fountain. I cannot find a suitable container for the base. I'm looking for a square or rectangle around 12-14 inches on one side that is not breakable and not too deep?

Youtube usually has some great diy tutorials/ideas...check that out.

( Plexi-glass can be cut and then glued making it water-proof)