Place a shower cap over your hair and head. Smear petroleum jelly all over your face. Mix two cups of water and four cups of Plaster of Paris into a large bowl. Stir and mix until the substance is a thick, white paste. Insert a straw into each nostril and recline your head onto a table surface. The straws will allow you to breathe. Close your eyes and do not move your face or head.
Have a helper smear the plaster mix onto your face. Be sure your entire face is covered. Allow 20 minutes for the plaster to dry. Wiggle your face muscles and joints with ease. The wiggling will loosen the plaster mask. Easily remove the mask from your face. Allow one day for the mask to thoroughly dry.
Measure the radius of your head from ear to ear. Glue an elastic strap to the sides of the mask commensurate with the measurement of your head.
Paint the mask green. Use various shades and tints of green -- along with other colors. Get creative.
Glue plastic horns onto the forehead of the mask. Glue buttons and beads onto the mask and paint. The buttons and beads will create a distorted look to the face. Make the mask as "monsterish" as possible.
Cut two pieces of cardboard sized to cover your chest and back. Paint each piece of cardboard green. Glue styrofoam pieces to the cardboard to resemble muscles. For example, glue two large thick pieces to the upper portion of the front piece of cardboard. Below the two large pieces, glue six small pieces to resemble abdominal muscles.
Repeat this process for the orc's back -- to resemble back muscles. Paint the "muscles" green, brown or black. Drape both pieces of cardboard with cloth. The cloth with cover the Styrofoam pieces. Staple the cloth to the edges of each cardboard piece and trim excess cloth. Spray paint the cloth green and shade it with alternate colors. You now have front and back pieces that resemble a strong muscular orc-like body.
Poke holes into the top left and top right corner of the front piece of cardboard. Repeat for the back piece of cardboard. Loop string through the holes and tie. Allow enough slack in each piece of string to drape comfortably over your shoulders. Put the mask onto your face and your front and back body piece over your shoulders.