I made a Spiderman Mask as it looked simple yet elegant and is also quite popular among people.

Supplies

Paper Clay
Acrylic Paint and Paintbrushes
Clay Tools
Base
Primer
Varnish
Paper Tape

Step 1: Giving the Mask Its Shape

To start with you have to take a sufficient amount of clay after which you roll it up into a ball and then flatten it to a thickness of your choice and place it upon the base while giving it the shape you want your mask to have.

Step 2: Creating the Permanent Details

Apply some water to make the clay moist and use your hand or clay tools to make a few details such as the eyes, or for example the black lines in my mask. Also do remember to create holes for the eyes, as a mask through which you can't see would be pretty useless.

Step 3: Putting a Layer of Primer on the Mask

Wait for the clay mask to dry off, after which put a layer of primer and wait for it to dry.

Step 4: Painting the Mask

Use the acrylic paints to paint your mask to your satisfaction keeping in mind small details which may enhance the overall appearance.

Step 5: Finish

Wait for the paint to dry and your mask is ready! Place the mask on a stand and your mask is ready to display!