Other easy designs you could try are flowers, fish and dragonflies.
You will need:
Black paper
Tissue paper or irridescent film (assorted colours)
Scissors
PVA glue

Draw your design onto black paper. If you don't have black paper, other colours should look fine too or you could even cut the design out of a cereal box and paint it black.

Use scissors to cut out the butterfly and then enough small squares of tissue paper (or irridescent film) to cover the entire design. Cover the butterfly with a thin layer of PVA glue.

Stick on the tissue paper squares, ensuring there are no gaps left. Leave it to dry.

Trim any tissue paper which may be overlapping the edge of the butterfly and the stained glass window is finished! Stick it to the window with a little bit of blue tack.
Butterfly stained glass window template (right-click and save to computer before printing):
