To make vol au vent cases, defrost pastry, roll out.
Decide what size you want, find appropriate "cutter" for overall size, this could be a tea cup, coffee mug, pint glass, whatever! Find another "cutter" slightly smaller, wine glass, sherry glass, egg cup etc etc.
Cut 2 rounds with the larger cutter. The cut out a circle from one of these with the smaller cutter. Using beaten egg as glue, place the sort of hollow ring on top of the other large circle. "Knock up" the sides with a knife to make them rise. Bake in oven according to temp. advice on packet. With the small circles that you have cut out of the second round, either bake these separately to put on top of the filled vol au vent, or if you don't want them to have "hats", squidge them up with the rest of the pastry and roll out again!