what do you use when you're practicing piping?

[pastrypez]

I've been practicing my piping at home using paper cones and sheets of acetate that I got at an art store and royal icing and it got me to thinking what other things people use when they practice at home?

At school right now I'm working on chocolate so doing lots of filigree (or attempting to)!

[EagerBaker]

I usually practice with an all shortening buttercream and disposable decorating bags. It is cheaper than using butter, and as I finish one design I just scrape it up from the wax paper and put it back in the bag. I never use this for anything else. The american buttercream that I use on my cakes is either half and half or all butter. I need to practice more with royal icing, but I have yet to need to use it for any of the design that I have made. I tend to make specialty cakes or wedding cakes.