Cut short sections from a synthetic hair piece that matches your natural hair color. Try to make them around the same length.
Clean and dry the part of the upper lip where you would like the mustache to sit.
Apply an even coat of spirit gum to a small area above the upper lip. Tap the area with your finger until it becomes sticky.
Begin pressing the cut prosthetic hair pieces to the sticky area using a makeup brush. Try to press only one end of the cut hairs so that the other end flairs out, much like a real mustache would. Apply enough hair that it covers the skin underneath.
Repeat steps three and four until the entire upper lip area is covered.
Pull the free ends of the hairs slightly with a makeup brush so that they detach from your skin and other hairs. You may wish to apply more spirit gum to balder areas.
Slowly peel the entire mustache off of your face, once the hair is the right consistency and the spirit gum is dry. Once off, you may apply another coat of spirit gum to the back of the mustache for a stronger foundation.