Designed by Carmel D. Morris, this is similar to her Stealth Glider (see her book 'Paper Spacecraft' on Amazon). This critter sure glides nicely and would spook the cr*p out of anyone as it flies past! Use A4 paper (or trim a half inch off the edge of a sheet of regular copy (letter) paper.

The video shows a modified version of her bat. The line images show a slightly different version. Experiment by following the video and the line diagrams and see which model you prefer. Basically the video version has the bat with a 'fuselage body' area where you can grip the model and throw it harder.

Step 1: Fold the Basic Bat Wing

It's important to watch the video so you can see more clearly how this fold is done.

With paper facing you as shown, fold in half.You can fold in half both ways to establish the wing crease coordinates (as shown in the video) -up to you, the model performs just as well.
In 2, for the upper flap, make two opposing diagonal folds from their opposite corners and then unfold. Make a vertical crease fold up to where the diagonals intersect. Now carefully bring the sides together. The video shows this more clearly.
In 3, make a vertical crease to form an 'ear'. This is shown in the next Step.

Step 2: Complete the Basic Wing Shape

In 4, swing the 'ear' to the upright position, push on the pointy fold and flatten it out.
Image 5 shows the 'ear' opening out. Flatten firmly and make sure it's symmetrical. The video shows an additional locking fold but some find it difficult. It sure helps to experiment though! Now repeat the wing shape for the opposite side, however there will be a slight difference...
In 6, open out the upper flap wing section.
In 7, fold the underside wing tips to meet their respective diagonal fold lines. The fold is shown in the next Step.

Step 3: Finish the Bat (before It Finishes You!)

Image 8 shows the bottom flaps folded to their respective diagonals. Now fold the bottom sections up along the bottom edge.
In 9, collapse the upper wing section; it should fold easily back into place.
In 10 fold the entire top section down by 1.5cm or approx 3/4 inch. You may need to experiment a little for correct balance. Now fold along the center and crease it well, and then have the wings out at a shallow Y angle.Note: The video shows how to make the center of the bat into a 'fuselage' which may help you throw it, however the bat flies well without it.
To fly, hold with finger and thumb along center of bat and with a gentle motion of your arm gently release your bat! (With a slight push for a smooth glide.) If you want to freak someone out, make the fuselage as shown in the video so you can throw it harder and it'll fly erratically, it's wings flapping, just like a spooked bat in a cave. You can adjust the bat's behavior by changing the angle of the wings. Make a lot of these for your next Halloween party and get your friends to fly them all at once :)