A 4-foot tall conical model volcano can be an exciting centerpiece for your float. Building a float-size volcano is a process and you’ll need to schedule your time accordingly. Drying time of at least 24 hours may be needed between applying papier-mache layers and painting and landscaping your model. Spectators can more easily see your volcano if it's elevated, so set it on a pedestal on the float. Of course, eruptive power can be pretty exciting, but that’s a whole different project.
Add a round cardboard or plywood base to the bottom of the volcano for extra stability.
Get a piece of chicken wire that is about 3 yards long and 4½ feet wide. This wire mesh will act as the frame for a 4-foot tall conical volcano.
Cut a 6-inch diameter hole in the center of the wire sheet to accommodate the mouth of the volcano. Using an appropriate pair of scissors, start at the center of the wire sheet and cut eight equally spaced 6-inch straight lines. Fold back excess wire to shape the mouth. Use the scissors to crimp excess wire onto the sheet.
Shape the wire mesh into a cone. Fold the excess mesh underneath the base and crimp to the inner sides.
Cover the chicken wire frame with brown paper that is slightly stiffer than a grocery bag. Tear 12-inch wide sheets and crumple it up first for a rugged realistic texture on the volcano. Attach the paper to the wire frame by tearing 1-inch end strips and poking them through the wire.
Tear about 600 1-inch wide newspaper strips.
Prepare your papier mache mixture. Mix by hand one part flour to two parts water in a large bowl. The consistency should be like white school glue--not runny, and not thick like paste. Add more flour or water to the mix as needed for the right consistency, and remove any lumps.
Coat the newspaper strips thoroughly with the flour mixture. You want the strip to be wet but not dripping, so gently run it through your forefinger and middle finger to remove the excess.
Attach the papier mache strips. Start at the volcano mouth, and allow the strips to go inside the mouth about 4 inches. Gently press the strip into place on top of the crumpled paper. Add additional strips in an overlapping fashion until the entire top portion is covered. Continue covering exposed pieces of the volcano with the papier mache strips in this same manner, overlapping all areas. Allow the layer to dry overnight, using a fan if necessary.
Repeat the above step to allow for three papier mache layers, allowing one day drying time between layers.
Add texture and paint to the volcano. Glue small pebbles onto the surface for a more realistic effect. Paint bright red lava flows or paint a design according to your float motif. Place the volcano on the pedestal of your float. Place dirt and tree branches around the base.