Unroll surface hold on curve please hep me

I make box with lines and curves. When i unroll box the curve dont true. How can hold them true with curve i draw.
Please help me!

ask.3dm (108.3 KB)

How are you unroll the surfaces? Are you using UnrollSrf and setting the tolerance large so that it unrolls?

How did you create the flat shapes on the right?

The curve you highlighted is a straight line and an isoline the original shape. UnrollSrf keeps the set of isolines which are straight (degree 1 direction) as straight lines when it unrolls the surface.

Your curved surfaces have double curvature which cannot be unrolled exactly. These types of surfaces are called non-developable.

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Thank you!