Measure the distance between your ears across the bridge of your nose, and the distance from the top of your forehead to your mouth. Transfer these measurements to a piece of poster board and cut out a rectangle.
Measure the distance from the top of your forehead to your eyes, and the distance between your eyes. Use these measurements to place ovals for your eyes on the poster board.
Draw a slot in the mask for your nose. Draw the outside of the mask along the edges of the rectangle in a free-flowing curved design. The outer design should generally follow the shape of the rectangle, but does not need to touch the edge of the rectangle. For example, the design could be a series of semi-circles joined together to roughly make a rectangular outline. You can make the outer profile of the mask as simple or complex as you want.
Cut around the outer design of the mask, and cut out the eye holes.
Cut a piece of elastic about eight inches long and staple it to the sides of the mask.
Glue decorations such as feathers and sequins to the front of the mask. You can use colors that will compliment the rest of your costume. You can also use markers or paints to decorate your mask. Let the mask dry and enjoy your own Carnaval party.