I suggest a remarkably useful device: Four circular disks when attached to a cart make it easy to move the cart from location to another. Furthermore you could

I suggest a remarkably useful device: Four circular disks when attached to a cart make it easy to move the cart from location to another. Furthermore you could put goods in that cart and move them too. A lot easier than carrying the goods on you back or an animal. A brief search of the internet finds this is a new idea.