Here's how to make an ornithopter powered by a rubber band.

You will need the following: (All my measurements are in inches.)

Wood: (Balsa works well, but i used coffee stirring sticks)

2 x 1 in.
2 x 1 1/2 in.
1x 2 1/2 in.
3 x 3 1/2 in.
1 x 4 1/2 in.
2x 5 in.

Wire: (paper clips work well)

1 x 2 1/4
2 x 2
1 x 1 1/4

Other Stuff:

Rubber Band
Super glue
Needle nosed plyers
beads
glue gun
Tissue paper (Other light materials work.)

Step 1: The Body

First, cut out all of your wood and wire, Then start Gluing together.
Take your 4 1/2 in. stick and glue on the 1 in. sticks as shown in the picture. Then glue the 2 1/2 stick across the top.

Step 2: The Tail

Then glue your three 3 1/2 pieces together in a triangle.

Step 3: The Wire

After that, bend your wire as shown in the picture above.

Step 4: The Beads

Now you can glue your beads on and put the wire pieces on (don't glue the wire! they should turn freely.)

Step 5: Tail

Glue the tail wire piece on.

Step 6: Wing Spars

You'll need to glue the 5 in. sticks to the wire pieces. then take the 1 1/2 pieces and punch two holes in the end and slip the ends through as seen in the picture.