If the front part is made of 6 mm (1/4 ") wide sticks with slight taper in ends, like Sigk has done with the canopy frame, it will work even without a former.
That is more work of course and requires more finishing, but end result will be better, too. Been there, done that

If you are going to use balsa sheet it will obey rules of physics just like Mike has explained in previous posts.

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