Gents - this is the method I've been using for years and it's about foolproof.

I always build my wings in two halves, joined at the center.
This is how I did the Cardinette wing.
Make up two end blocks as shown.
Slide the ribs onto carbon fiber arrow shafts. (holes should be previously drilled in the ribs.)
With the ribs properly spaced, clamp the shafts down to the end blocks.
Glue on the trail edge strips.
Stand the blocks up vertically.
Note that I DO NOT USE a lead edge spar. Being so close to the neutral axis, it contributes virtually nothing.
Now, make up some 1/16 planking that will go all the way around the nose of the ribs, extending back around 1/4" past the spars.
Soak the planking in HOT water for around 1/2 hour.
Take it out of the water and blot it dry.
Gently coax it down over the ribs.
Starting from the middle, tape the planking down, attaching the tape to the shafts.
Let it dry overnight, remove the tape and you will have a perfectly formed lead edge.
Glue it on, trim it and that's it.
Remove the shafts and do another wing.
Align and join the two halves, put on the capstrips and you're ready to install the controls.
Once you've tried this, you may want to do all future wings by this method.
I made the entire Cardinette wing in four evenings.

By the way, the next CL World will have a complete article on the Cardinette, outlining this same procedure.
Bob Z.