before you ice them? I just covered my square cake dummy with contact paper but I have air trapped underneath and it doesn't stick to the foam completely. I want to cover them so I can practice icing them with buttercream and just be able to clean them easily. any other ideas beside contact paper?

Corn Syrup but it will stick really good! Piping Gel

Nothing. Scraping icing off of a dummy isn't difficult, and they wash up easily without a covering. Contact Paper isn't foodsafe for prolonged contact, but I assume that you wouldn't consume re-used icing from a dummy anyway because it could get styrofoam balls in it as well.

Using dummies to practice icing skills on isn't the best option because it's not the same as using actual weighted cake... a completely different ball game.