Spartan helmets were worn by the Spartan warriors to protect them from a foe's savage blows and to intimidate their enemies. You can make a cardboard replica of a Spartan helmet so your child can re-enact famous battles or to add to your costume for a party.
Measure the circumference of your head. Use a pencil to mark a pair of lines on cardboard whose width is equal to half your head's circumference at the widest location. Add a line 1 inch outside of the first line and cut along this outer line.
Cut one end of the cardboard so the corners are rounded into a semicircle. Bend, roll and flex the cardboard in every direction so it does not always bend along the corrugations.
Cut the helmet out of the cardboard at the second line you traced. Make cuts 2 inches apart in the cardboard so the cardboard can curve. The first cut should start at the top of the semicircle and go down 5 inches. The cuts 2 inches to either side of this 5-inch cut should be only 3 inches deep, radiating out from the imaginary center to the radius of the helmet. Alternate 5-inch and 3-inch slits until the slits go in a half-circle all the way around the end of the helmet.
Bend and work the cardboard so it forms a half-bowl shape. It may help if you crease the tabs sticking out in a radius from the top so they curl toward what will become the center line. Use the hot glue gun to glue the cardboard together to make a bowl shape at the end of the cardboard that will form the top. Bend the cardboard and overlap the edges all in the same direction.
Push the bowl side into a salad bowl while the hot glue cools; it will help the helmet retain its shape. If the glue is not coming out fast enough, you may have to push the glue stick into the gun with your thumb (being careful not to touch the gun or hot glue). Allow the glue to cool completely while holding the pieces in position.
Make the other half of the helmet, repeating all of the previous steps. Try to make all of the cuts line up and everything the exact same size. Put this half together with the other half without gluing it to see how the pieces match up.
Add a strip of cardboard 3 inches wide and equal in length to the distance from the back of the helmet to the tip of the nose. Glue this piece where you were measuring, on the inside of both halves of the helmet. Trim the piece of cardboard that sticks down between your eyes (after removing the helmet) so that the piece covers your nose but does not obscure your view.
Cut a 6-inch-wide piece of cardboard that needs to be the same length as the distance from your cheekbone to the center of the back of your head. Cut a slit into one corner that is 2 inches deep, 2 1/2 inches from the corner toward the far end.
At the adjacent side, make a slit that starts 3 inches from the same corner as before and ends at the deepest part of the slit that you cut just prior to this so that a chunk is removed from the corner. Glue this flap inside the helmet so it covers the neck and cheekbones. Trim the helmet as needed to fit your face (eye location, mouth width, etc.).
Decorate the helmet. Make a plume of cardboard by cutting several 2-inch strips and bunching them together so they get longer going one direction. Apply hot glue between all of these pieces of cardboard and then glue a band of cardboard around all of the strips before gluing it on top of the helmet. Cut the edges of the plume a little rough so that they seem more "organic" in design than the rest of the helmet.
Estimate the location of the center of your ear by tapping on the cardboard with a fingernail. Mark this location with a light crayon mark so that you can cut an ear hole. Start by cutting a hole smaller than what you need so that if you are off a little bit, you can adjust the location. Gradually widen the location until it allows you to hear without letting your ear stick out of the hole. Next, cut tangential slits from the hole on either side down to the bottom edge of the helmet.
This helmet is not a safety device. Never cut or glue the helmet while it is on anyone or place sharp/hot objects near the face. Wear goggles at all times when working with sharp or hot objects or if the eye is at risk in any way. Do not put on or use the helmet until the glue cools completely. Cardboard is flammable.