Commercial latex masks are made through a process of sculpting, moulding and casting. This process is time consuming and expensive, and is not worth it for a single mask. If you want a custom latex mask, you can make one with liquid latex and cotton. By gradually building up layers and features, you will slowly but surely make an original creation that looks like whatever you want.
Spray a large styrofoam head with three thin coats of Crystal Clear spray sealer. This will prevent the latex from bonding to the styrofoam.
Draw the eye, nose and mouth hole locations onto the head with a permanent marker.
Brush a thin coat of liquid latex onto the head with a cheap paint brush.
Allow the latex to dry. You can use a hairdryer to make the drying go much faster.
Apply another thin layer of latex, drying it as you did the last one.
Build up 10 to 20 layers of latex, depending on the desired thickness.
Pull several cotton balls apart into loose tufts. You can also use cotton batting, if desired.
Brush the first area on the mask where you want detail with latex, then press the cotton in place. Form the cotton into the desired shape with your fingers, then brush more latex on top. Continue to work the wet cotton until you reach the desired shape. Larger shapes, such as pointed noses, may need several layers of latex and cotton to build up.
Continue adding latex and cotton until you have built up whatever features that you want for your mask. Allow the mask to dry when you are finished.
Tear the straight edges off of several pieces of tissue paper.
Brush another layer of latex onto the mask, then smooth the tissue into it. This will form a smoother skin than is possible with cotton alone.
Cover the entire mask with tissue skin, then paint a final layer of latex to encapsulate it.
Allow the mask to dry overnight.
Paint the mask with paints designed for latex, available at many art stores.
Cut a slip up the back of the mask to remove it from the head form. Cut out the eyes, nose and mouth before wearing.
Wrap the brush in cling film between layers to prevent the latex from drying and ruining the brush.
Do not allow liquid latex to get into your hair or clothing. It will be impossible to remove.