I confess I haven't read this whole thread...but you were asking for suggestions, and while I haven't read any, I have some.
I'm looking for a glass tank that would be easy to fill. Maybe something with the drip tip and top end cap all as one?, where you could just pop the top off the tank, drip and put the top back on...Wooola! Done! There are some of us who are........well, getting older? lol! I know NOTHING about shaping glass, so I don't know if this would even be 'doable'...but these are just suggestions. I'm not too crazy about the tank I saw on the first two pages...while something like that might work for some, here on the farm, something like that would be apt to hang up on too much farm equipment...lol! What I'm looking for is ease, functionability and looks. Maybe make different colored tanks? Swirly colored glass? or even MAYBE the cracked glass look...dont know if you'd be able to do that one.