On the ribs I made for my Hatz project (the one that gathers dust in the basement), I used a piece of PVC pipe with a cap on the end, filled it with water, just soaked the capstrips for an hour or so. When they came out, I then put them in a press I'd made, clamped them in the press overnight to dry, then pulled 'em out the next day, curved and ready to go.

The press was a 2' chunk of 4"x4" that I cut into lengthwise on the bandsaw. The lengthwise cut was a top airfoil template. I put the capstrips between the two halves, then clamped them so the strips would dry into the airfoil shape.