Select one to three different width and design ribbons that match your party decor. A typical cupcake box is four inches deep, so don't select ribbons that combine to exceed this width.
Measure the outside diameter of your cupcake box with a flexible measuring tape.
Cut the selected ribbons to the measured length with scissors.
Run permanent two-sided adhesive tape around the circumference of the box where you will be attaching the ribbons.
Starting at the back of the box, press one edge of the first ribbon onto the adhesive tape and slowly attach the ribbon to the box. Attach the rest of the ribbons to the tape in the same way.
Remove the cupcake papers from their packaging, place them with the center bottom portion up and place a heavy book on them so that the sides fold outwards and flatten. Flatten enough coordinating cupcake papers to cover the cardboard surface of your boxes.
Practice arranging the papers onto the box so that they overlap and cover the plain box. Set aside the papers after establishing a working pattern.
Apply a light, even coat of water-based decoupage medium to the cardboard surface with a paintbrush.
Brush the back of the cupcake papers with additional decoupage medium and apply them to the box. The additional medium assures that the overlapping surface areas are covered and will adhere to the other papers as well as the box.
Remove any creases and bubbles in the papers or medium by pressing the flat edge of a metal ruler over the entire surface.
Allow the box to dry for 15 minutes before applying a light sealer coat of decoupage medium over the papers with a paintbrush. Allow the sealer coat to air-dry for 30 minutes before handling the box.
Measure the width, length and depth of each portion of your cupcake box with a metal ruler or flexible measuring tape.
Transfer the front, back, sides and top dimensions onto a sheet of clear plastic with a fine-point permanent marker and a metal ruler as a guide, creating the outside rectangular or square shapes that your design will fit in.
Sketch or trace your stencil design onto the clear piece of plastic with a fine-point permanent marker.
Color in your stencil pattern with colored markers to match the colors you will be using on your cupcake boxes, keeping the pattern as simple as possible. This will give you an idea of how the colors you've chosen will look; you can change the colors before actually applying them to the box if you wish.
Cut the stencil out by placing your plastic sheet on a hard wooden crafting surface and pressing the sharp edge of a craft knife along the outside perimeter of each colored section and the outside perimeters.
Attach the stencils to the cupcake box with painter's tape at the top and bottom edges, being sure not to cover any open areas on your stencil.
Paint your design within the stencil shapes onto the cardboard with a detail paintbrush dipped in acrylic craft paints. Allow the paint to dry for thirty minutes before carefully removing the stencils from the box.