I have done 20 gal
TV tanks. We had plans of a 10 gal
TV tank but never got started on it and now I no longer live with the guy that I was helping make the tanks.
The biggest items when making such a tank are the following:
How to light it, we light the tanks from above so that means having a few inches clearance.
How to access the tank to clean and service it. We did this from above also. So that meant having an access port cut in the top of the console.
Supporting the weight of the water. Its less important the smaller you go with your tank but I like to consiter a weight of 10lbs or more per gal
when you factor in substrate and decorations along with the 8lbs per gal