Hi, Hagen has a glass 'cube' (mine's l8" x l8") with doors that start about 1/4 of the way up one side (only) to allow water in the bottom. Yes there's a 'seam' of course - black edging - where the glass meets the bottom of the doors and where they meet in the middle, as well as around the top and bottom of the cube, but the opening is only on one side, and the rest is just glass (the top screened for ventilation).

One option might be to have one large door that either opens upwards like a car's trunk (or if you're really handy & ambitious like a lawyer's/barrister's bookcase) or that opens downwards. This would eliminate seams running through the very middle of the tank's front glass.

Another option, though not as convenient as front doors would be side doors. This would eliminate the seams in the front.

I don't know how large you are thinking, but {{gwi:568366}} are some pics of my large viv. Maybe it will give you some ideas.

-DH