weight of a beer-box

As some friends and me are thinking about creating a remote controlled VTOL-beer-box (VTOLBB??) I needed to measure the weight of a standard 24X0.33l beer-box. Lacking a scale, my engineering skills were needed (*grin). Using a chair, the stick of a broom, a small garbage-bag, some pieces of string and 1l of water I build this improvised scale.
Not caring about the weight of the strings (should be roughly same on both sides) and the garbage-bag (nearly no weight) I compared the beer-box to 1l of water (~1kg if it were 4deg celsius in my room, but negligible less at 20deg celsius, which, I guess, is outweightened by the solved minerals), measuring the distances from the point of momentum-equality.

The result was roughly 2.11kg for an empty Jever 24X0.33l box. By getting rid of some of the inner material we should be able to lower this down to ~1.5kg.
Using four impellers it would be possbile to lift this weight. The biggest problem will be to stabilise the whole thing! Another option might be to use two counterrotating rotors, either with cyclic control or some kind of flaps mechanism.