You can do the placecards or use one 5 x 7 frame to make a menu. Even if it is only three flavors, you can name the flavor and add a description that will help with allergy alerts. At the bottom you can add the allergy disclaimer for your bakery. I use an ornate silver frame. I also have a variety of placecard holders. It's whatever the client prefers. I also have the silver frames that hold a business card. They can stand on their own or on a tiny tripod.
For my buffets ( and I bundle in the little 3-flavor events), I employ a graphic design artist to make appropriate cards. These are beautiful and completely coordinate with the event. They are usually several pieces of layered card stock with beautiful fonts, ribbons, and a colored crystal.