The local supermarket doesn't sell the paper cases used for making cup cakes and other similar baked goods. They do sell baking parchment though, so I whipped this up in Openscad.
I designed it to be printed, but as I do not yet have a 3d printer this is still untested.
Thank you to everyone who commented on my things! A big thank you to MakeALot who pointed out that something wasn't right with the diagrams. Details in the updated code.
Print all the parts,glue the handle to the plunger, then press circular pieces of baking parchment into the base using the plunger... Cupcakes!