[ajgriff]

It's the uncooked pizzas that are sold by supermarkets in film wrap that often have the polystyrene discs.

The matting mentioned by John is also sold cheaply as non-slip drawer linings in rolls and is usually black. It makes even better turntable mats although is trickier to cut to shape.

When experimenting with different turntable mats for higher quality equipment it is, of course, important to adjust the arm height to suit.

Alan