Pre-heat the oven to the temperature on the instructions to your oven-bake clay.
Cover the baking sheet in foil.
Draw an outline of the door you want to make on a piece of paper. You want the door to be at least 6 inches tall and about 4 inches wide -- it does not have to actually match the height of any gnome sculpture you have in place. Don't forget to add a window -- and be sure to shape to allow for tall pointy hats. Cut out the pattern with scissors.
Lay wax paper or some other kind of paper on your work surface to protect it from the oven-bake clay. Because the clay is non-edible you need to protect any surface it comes into contact with especially if it is usually used for cooking.
Knead the clay between your hands until it becomes soft and easy to work with. Flatten it out with your hands until it is a little bigger than the size of your door pattern. You can use something besides your hands to flatten the clay, like a rolling pin or bottle, though the uneven texture of hand-flattened clay lends character.
Lay the pattern on the flatten clay. With the tip of a skewer, draw into the clay around the pattern.
Remove the pattern from the clay. Carefully remove the excess clay from the door with a butter knife or clay-cutting tool. Smooth out the edges with your fingers.
Work a small amount of yellow clay until soft. Again, use your hands or a roller to flatten the clay.
Cut out the window from your door pattern. Lay it on the yellow clay. Draw around it with the skewer and remove the excess clay with a knife or tool. Place the cut-out window onto the clay door.
Roll the excess door clay into a thin log. Lay the log onto your covered surface and roll it into a thin, long snake. Use the snake to outline the window and edge around the door for detail.
Roll a small amount of another color clay into a tiny ball for the door's handle. Place on the door.
Move the completed door to the foil-lined baking sheet. Place in the oven and bake for 20 minutes. Remove it and let the door completely cool.
When cool, glue one skewer to the back of the door with the pointed end down. Let the glue dry completely. The skewer allows you to set the door into the dirt and helps keep the door upright.
Brush on a coat of marine varnish with a brush. Let the piece dry. The varnish weatherproofs the piece for outdoor use.
Place your finished door at the base or a tree, large rock or at the foundation of your own house.