Where are the handles?
I haven't gotten that far -- I initially assumed that I would not be able to add handles, due to the weak strength of the wall material. One solution for handles may be to use rope that goes into re-enforced holes. It would be best if the ropes go through the entire hive, so that the hive walls are squeezed towards each other when you pick up the box. If the ropes only go through the one wall, when you pick up the box, it will have the effect of pulling the walls away from each other.
In a previous version of this box (which existed only on paper), each styrofoam box had a 1 cm thick wooden shim underneath it that stuck out about 5 mm from the side of the hive, and it would have been possible to pick up the boxes by grabbing the shim as if it was a handle. I may still do a version that uses the shim.
I was originally concerned about the surface hardness of my painted polystyrene hives too... a more consistent surface which becomes modestly hard with a couple layers of latex paint.
I had the same experience with my one poly nuc box -- paint hardens the surface: