Mix a small amount of colored polymer clay with a large piece of translucent polymer clay. Use more for your background color (in the moon and stars sun-catcher, blue) than your image color (yellow)

Thinly roll out the clay you want for your image, and cut out the pieces

Roll out your background color to the same thickness, and trace out where you want your images

Take out the cut out pieces in your background color, and replace them with your images

Blend the pieces together, being careful not to distort the image

Cut the edges of the background into the shape you want, and outline with a roll of opaque clay. Remember to add a hole so your sun-catcher can be hung up.

Bake according to the directions on the polymer clay packaging

Add a string/ribbon/chain/etc. and hang up to a window!