Because it's becoming laborious and painful tying nylon wire to the top of the cube, I decided to cover it in a large net, which I could hang prints and anything else in really easily using the box clips. 

I found a bird net on Amazon and managed to put it over the top of the cube using staples and cable ties. So far, it's working great - hooray!

For the print you can see in there I've clipped a ruler as a weight to the bottom of it, since it was curling inwards and upwards. This will have to be something I think about for when I hang more.