Durable paper airplane glider with rubber band launcher

Cut out the pieces. You can make them from any paper but make sure you use enough layers. Play around with different colors for a personalized design.

The two small wooden pieces seen in the picture are used to reinforce the front and rubber band section of the airplane, which are under most stress. 
I had some leftover 1mm balsa wood so I thought it would look very nice with a wooden detail. But you can use cardstock paper, just add two layers (default in the xcs file).

The body needs to be 1mm thick when the layers are glued together. This is important for the tail wing as its slot is just over 1mm wide.

The wings can be thinner but aim for at least 0.5mm of thickness. You don't want them too thick. Try to get about ⅔ of layers used for the body.
The tail wing should be thinner than the main wing to keep its weight down.

When cut be mindful of charred edges. Take a slightly damp sponge and carefully wipe the edges only.

Apply glue to body sections. Glue needs to be applied evenly over the whole area.

I use slightly diluted wood glue but this tends to curl the paper and takes a while to glue. It does provide a very strong and durable bond.

I recommend placing the glued piece between two non stick layers and weighing it down or clamping between two flat pieces.
You need to ensure the parts are dried as flat as possible to make the plane fly nicely. 
I use two laminated pieces of paper and weighed it down with a few heavy books. Waxed baking sheet would probably work just as well. Just make sure it won't stick and to use flat things.

If using only one layer for the tail wing, skip this step. I initially cut out two layers but after trial end error found that only one layer works better.

Repeat the same process as when gluing the body part. Weigh down the pieces while the glue cures.

You have two options. Either glue the wing flat and bend it after or bend it beforehand and glue pre-bent. The pictures are of the second option.

Gluing it flat is easier but makes for a worse wing. Repeat the same process as for the body and tail wing. Once the glue fully cures, bend it along the center line. Since it was glued flat, the wing will want to straighten so you will likely need to adjust is regularly. Try to crease the bend so it stays in shape.

The better but more difficult option is to pre-bend the wing and glue it this way. Apply a bend along the center line. Glue all layers together. Clamp each half separately and make sure the bend is applied while the glue cures. Once the glue cures, the wing will keep its shape.

The bend should be around 10-15 degrees for each half. This means that each tip should be lifted by about 17-25mm from the base.

Also sandwich and clamp the piece to keep it flat. I used flat cardboard pieces taped over with packaging tape. This makes for a non stick surface.

If you didn't align the body well the edges won't be aligned and will make it more difficult to glue in the wings. In this case take a fine (high grit) sandpaper and lightly sand around the edges to square them up.

Glue the main wing on to the body. The wing should start where the side reinforcement ends. The flatter part with the curved tips is facing towards the front.

I used wood glue but added two small dots of gel superglue in two points. This helps keep the wing on the body while the glue dries. 

Add the glue and use the center line on the wing to align it to the body. Try to align as best as possible to make it fly well. I visually make sure the wing is squared to the body and then turn it upside down. Then I make sure the body is perfectly vertical and leave until the glue dries.

For additional reinforcement ass a bead of glue along the bottom edge on both sides. Additionally, you can cut a small paper strip, glue it on the body/wing joint to reinforce it. I didn't do this as I felt it was strong enough.

Similarly to gluing the main wing, glue on the tail.

I again used a dot of superglue to hold the wing in place initially and added a bead around the joint. You can (hopefully) see the thin glue line with a small dot of superglue in the picture.

It is important to try and get it as square to the body as possible.

The handle doesn't require any work but you can paint it. 

Source a rubber band and once the glue on the airplane is fully cured, you are ready to go outside and play. I found that a larger but weaker rubber band works better than smaller stronger ones.

The airplane is intended to be launched with a rubber band. Hand throwing won't make it fly well but with some adjustment as noted at the end it may be possible (but not as fun).

Depending on how the plane flies, you may need to make adjustments.

If it instantly falls down on its nose, it is too nose heavy. Try to add some weight to the back to balance it.

If it instantly curves up, it may be too tail heavy. Try adding some weight to the front.

In both cases the wings may be the issue, check if they are straight first.

If it curves in an arbitrary direction, check if the wings are aligned. You may need to bend them to get it to fly straight. Of bend them to fly in a curve. 

Some trial and error may be required.