This instructable will show you step-by-step how to put one together, and I envision this as a parent child activity. I've added a note about that at the end.
Step 1: You Will Need
For the body:
Paper - Fine paper is nice, but newsprint or butcher paper will do and can be painted
Mask - Download the pdf template
For the Mechanism:
1 wooden spool - Still available at hobby/craft stores
1" finishing nail
1 rubber band
6" wire - Paper clip works, but I use 14 gauge galvanized wire for a bit more stiffness
40" heavy thread - embroidery thread works well
1 finger pull of some sort
Step 2: We'll Start With the Mechanism
Step 3: The Spool
Draw the rubber band through making sure it will be straddling the nail. I drive the nail in first just until I can see the point.
Drive the nail in leaving 1/16" or so above the surface, but make sure the spool rolls without the nail touching the ground. The nail performs two jobs. It holds the sides rubber band apart so it will wind, and it provides an anchor for the pull string.
Cut ~40 inches of thread. Tie a loop in the end of the thread and cinch it down on the nail. Use a spot of super glue to fix it in place. After the glue is dried, wind the thread onto the spool. While you're waiting for the glue to dry, move onto step 4.
Step 4: The Wire & Finished Mechanism
Cut 6" of wire or unbend a paper clip for the harness.
Bend it according to the template on the mask .pdf and, using the notches anchor the ends if the rubber band with the wire straddling the spool.
Set the mechanism aside.
Step 5: Dragon Tail
Cut a 5 1/2" wide strip of paper, then accordion fold it. There are any number of ways to do this, from a simple accordion fold to more complex mountain and valley folds. I will try to pull together either some instructions or some links for you.
Step 6: Dragon Mask & Finished Body
Poke holes at the sides where indicated and on top for the pull string.
Glue the tail onto the body at the underside of the mask. You will need to curve the mask for this so you might want to attach the mechanism to assist. (Step 7)
Step 7: Attaching the Mechanism
Poke the ends of the wire through the holes in the side of the mask orienting the mechanism so that if the string were pulled the spool would move the dragon backwards.
To add a little tension to overcome friction, rotate the spool a couple turns without pulling the string, the same direction the spool would rotate if you were pulling the string.
Feed the string through the hole in the top of the mask.
Secure the harness to the underside of the mask with tape. The wire gives the head its shape, so feel free to adjust it to whatever pleases you.
Step 8: Finishing Up
Now set it on the floor and pull the string! When you let the string go, the dragon should zip forward with a fun zig-zag glide.
Step 9: Followup
I realize this project as a whole is definitely beyond kids, but I also know that Cub Scouts is intended to be a parent child program. As such I think it is a great activity for adults and kids to attack together.
The mechanism and the dragon are really two separate sub-projects. The adults constructing the mechanisms with some help from someone with access to shop tools. The kids folding the tails with some help, and painting the mask. And the parents and kids working together to hook it up.
I am told that our pack will be doing these as centerpieces for our Blue & Gold Banquet in February, so we'll see if I can live up to my own expectations ;) I'll let you know.