A large disc with a textured non-stick surface, mounted on a spare wall in or near the kitchen. The disc has a prominent raised rim except at one point (which is at the bottom of the disc when it is hung correctly) where there is something resembling a pouring lip.

The method;

Boil desired quantity of peeled potatoes in lightly salted water. Drain and allow to cool until safe to handle. Take spuds one at a time and drill out a small plug using an apple corer. Insert chunks of butter (preferably New Zealand but a lesser quality Northern Hemisphere type may be substituted) in the hole. Hurl / pitch / bowl the buttered spuds at the Wall Masher. Collect prepared dish from recepticle mounted below the unit. Wipe unit clean with tongue.