I was really surprised at how easy it was to make my own marshmallows and peeps. Just some really basic piping (and a really easy marshmallow recipe).
The marshmallows turned out just as springy as store-bought ones. I can't bring myself to eat them!
I talked a little more about how to do the piping on my blog: http://www.waywardgirlscrafts.com/2011/04/homemade-marshmallow-peeps.html