2 flaps from 1?

[Acorn Man]

I have an idea for a model I can modify, but I need to make 2 flaps from this one flap. It's about the size of a crane head but thinner. Reverse fold is all I can think of. The longer the new flaps the better. Thanks.

[Baltorigamist]

This requires a technique called point splitting, which you can read about in Origami Design Secrets.

[Kabuntan]

There is some data about it here too (on Dr Stephen O'Hanlon's website).