Anyone remember 'Stackajacks'

[iluvcatz]

They are rectangular boxes made of plastic boardlike stuff with what looked like a corrugated core with little plastic corner bits, this means you can stack one on top of the other without it resting on the stuff in the lower box. They came flat so you made them up yourself. I bought them in the 80's from one of the small ads they used to run in newspapers, (long since gone). I no longer have them and want to buy some more.