The classic costume of a "naked" person wearing a barrel is funny, but somewhat impractical if you use an actual wooden barrel. Instead, make a no-sew costume by spray painting a sheet of foam to look like a barrel. A foam barrel is less expensive and lighter than an actual barrel. The overall look is the same and is just as funny, but the foam is more practical.
Cut a sheet of foam with a box knife so that it is wide enough to loosely fit around your body. It is easier to wrap the sheet around your body loosely and have a friend mark where to cut the foam. Cut the length of the foam to your preference. Most barrel costumes fit right under the armpit area and hit the wearer just over the knees.
Spray paint the foam sheet brown in a well-ventilated area, and let it dry. Reapply another coat of paint if necessary.
Lay the foam sheet on a work surface longways, and paint lines on the foam going vertically to look like strips of wood on a barrel. For additional detail, use jagged strips of brown duct tape to simulate the boards or the cracks between the boards.
Apply a strip of the brown duct tape around the top and bottom edge of the foam and around the middle. This simulates the look of a barrel held together by the strips of wood or metal bands. If you prefer, use traditional duct tape or aluminium foil tape for this accent piece.
Roll up the foam sheet, and connect the two ends together with the duct tape. You might need a friend to help hold the foam together while you apply the tape. For added support, tape the inside of the foam piece with duct tape, as well.
Cut two pieces of elastic approximately 20 inches long.
Attach the elastic to the inside top of the foam barrel with duct tape. This will server as shoulder straps to help keep the barrel on your body. Position the straps so that the seam where the foam meets is in the back where it will be less noticeable.
Wear flesh coloured undergarments or a tube top and shorts -- the inside of the foam barrel might be itchy on you skin -- and place the costume over your body. Adjust the shoulder straps as necessary.
If you want a more modest barrel costume, make the barrel itself longer and cut arm holes in the sides. This will bring the "neckline" of the costume upward. Instead of purchasing a new sheet of foam, use the smooth side from a "egg crate" used on your bed.