A pie shell is an uncooked pie without filling. To make it, use a pie dish (crafted from soft clay or, more commonly, purchased) with pastry dough (made from combining flour and water). Players can fill a pie shell with any of several fillings, and then cook it on a range to make a pie.
Buying the pie shell components on the Grand Exchange and making these can be profitable. You gain about -322 coins per inventory (14 pie shells). Such a method however, is often hindered by the low supply of Pie dishes and flour.