You will need:
Here is the blue print - consult it for all dimensions. Here is a picture of the completed helix
First make the 4 streamers. I made mine approx. 2m long, tapering from 3cm down to 1cm width. Hot-cutting is great, but it is not really necessary for any of the Helix parts.
Now cut the 4 wings, 4 wing pocket strips and the central square. Cut out the hole in the middle of the square.
Sew a wing pocket strip to the leading edge of each wing: 'good'
side to 'good' side (it's a good idea to fold over the strip about
0.5cm at the beginning to reinforce it). The strip will be longer than
the wing; that's fine - we will just cut off the excess later.
Note: start the pocket about 1cm away from the inner edge (see photo); you will need this allowance to attach the wing to the central square without closing off your wing pocket.
Fold over and complete the pocket by a closing seam on the back side of the wing. When you get to the wing tip, insert the streamer in the wing pocket seam. You should now have a nice wrinkle-free leading edge pocket. Finally, cut off any excess wing pocket material at the wing tip.
Attach the wings to the central square. Cut spars to length, add end caps and insert in wing pockets. Attach a swivel (or 2 in series, if you're paranoid) where the spars cross and you're good to go.