Make a wood frame in the dimensions of the doorway with 1 x 3 lumber. Screw plywood triangles into the corners of the frame as braces.
Stretch an old sheet over the frame and staple to the back, starting in the middle of each side and working out to the corners.
Draw a scary face onto sheet with a permanent marker.
Wearing rubber gloves, mix a solution of one gallon white glue with one quart latex paint, and add one to two quarts of water. Stir together until it becomes the consistency of house paint.
Rip additional old sheets into two-foot wide strips. Dip strips of fabric into solution and wring out excess. Brush stretched sheet with paint solution, and lay strips onto face so that they drape in clumps and fold to desired texture. Leave eyes and mouth uncovered.
Once you’ve surrounded the eyes and mouth, cut out the majority of the negative space then slit small tabs that can be turned up into the folds. Brush with more paint solution.
Let dry for 3-4 days on a plastic drop cloth flat on the ground.
To add aged effect, brush on glaze medium tinted with dark brown paint. Let dry for one more day.
Once installed in doorway, you can add special touches like Spanish moss, rubber rats, and fake ivy painted brown for an extra-creepy effect.