If you're going glass then best to build it on-site on the stand where it will stay. The 2400x1200x15mm base panel for my tank was bloody heavy, and the entire tank would weigh close to 400kg. Not impossible to move, but very difficult! That said, the weight of the tank is only a part of the difficulty of moving a large aquarium, the big fish are even more of a problem! If you can build the tank on-site I wouldn't give too much consideration to weight unles you're planning on moving soon.