False noses can be made from a wide variety of materials, each useful for noses of a different purpose. A Silly Putty nose is fun for a bit of silliness, but it's also a perfect choice for a very specific type of special effect; use Silly Putty for plays or theatrical productions that call for a false nose that initially looks realistic, but then melts or squishes, causing the disguised character to lose his cover. Whichever reason you have for wanting a Silly Putty nose, the methods of sculpting one are the same.
Form a thick pancake from the Silly Putty. Roll the putty into a ball between your palms, then pinch the ball between your flattened fingers and thumb to form a disc about a half-inch thick.
Conform the Silly Putty blob to your nose. Line up one edge of the circle with the top of your nose (between your eyes) and lay the disc down over the bridge of your nose down to the tip, centering it. Fold the edges of the disc down over the sides of your nose, then flatten and blend the edges of the putty into your cheeks until there's a gradual slope from your cheeks up to the unshaped mass over your nose.
Shape the front and tip of the nose. Stand in front of a mirror and sculpt the nose as you want it to look. Start by covering and conforming to the shape of your own nose, coating the top of your nostrils (don't let any putty get inside) and pull a thin strip for the section of skin between your nostrils. Shape the false nose shape you want; make a large, bulbous tip, long pointy tip, or reshape the top of your nose to make it more hook-shaped by pinching the putty around the bridge of your nose. If you find you have more putty than you need for the shape you want, work the excess down to the tip of the nose and pull it off with a short, sharp motion (this will ensure a clean break), then re-form the torn away section to smooth it.
Blend the nose. Make sure the bottom nostril area tapers down to your skin and that the same is true at the top between your eyes.
Coat the nose in makeup. Apply theatrical makeup to cover the putty using a makeup sponge and a blotting motion. Use a coat of powder for more coverage. Skip this step if you want the Silly Putty to stay clean and for the nose to look like it's obviously made of Silly Putty rather than like a more realistic nose.