You may have heard of the 4 colour theorem that says you only need 4 colours to colour in any map so that no touching regions are the same colour. Give it a try! See if you can come up with a map that needs 5 colours. You can't.
But this is only true for a plane, like a piece of paper. On a torus, you actually need 7 colours. And what better torus to demonstrate this on than a mug?
The boundaries between regions necessarily go through the handle which makes this mug almost impossible to mass produce. The upside is that what we have he is beautifully hand crafted. As such, each mug will be slightly different. But the maths will stay the same.
Price = p367 pence = £24.77