LOL, I just laughed out loud...About 3 or 4 years ago I ordered 2 of those little "shopping-carts" from eBay for like $2 a piece shipped, a green one and a purple one..My Senegal has one inside of his cage that for whatever reason, I didn't teach him this, whenever I give him a whole almond or Brazil Nut as a treat, he puts them in his "shopping cart", and then when he wants them he goes and gets one out of the cart. Now if I could only teach him to put the empty shells back into the cart instead of throwing them all over the house....
The other one is underneath his PVC play-gym, on the piece of plywood I have underneath it, and he does "try" to push it around, as already mentioned it does work a lot better if it has weight inside of it...Kane is constantly flipping it over anyway, then he looks at me and starts calling me to come and flip it back over, and you can imagine how this goes on and on..