How to make birdseed suet?

Feeding the birds is costly. I would like to know if there is a recipe for making wild bird seed cakes. You can purchase wild bird seed by the 40 lb bags for ten dollars, but when you purchase the cakes to fit the wire feeders, it costs like $7.Surely there is a way to make them from the bagged seed to fit the blocked wire cages to keep the wild life happy!
Thanks