Step 1: Materials
A poly-boy is a 1m x 1m x 1m plastic cube with a reinforcing cages around it. It is used in industry to hold and transport 1000L quantities of liquids. I removed the plastic insert and just took the cages.
You also might need:
Castors (if you want to move it)
Some outdoor fabric (I used outdoor umbrellas I found on the side of the road)
Dirt & plants