baking in pyrex bowl or kitchenaid mixer bowl

a friend wants to make a "belly cake" for her oscar party for the juno dish. neither of us feel much like buying a pan just for this. would a pyrex mixing bowl work or am i risking life and limb? what about a kitchenaid bowl? i saw martha do a monkey cake in a stainless steel bowl...i have some cheapies from target, but they're very very thin.

cook times, recipes, and belly button (there's an innie/outie debate) suggestions all welcome!!