It's a bit poetic. The surfboard didn't exist. It was a slab of wood.
So he drew out the not-yet-existentent surfboard (the video shows this), and then he cut the surfboard out of the wood (as also shown).
It sounds strange to me too. "I cut it in to be." means (to me), "I cut into the wood so that the surfboard that I had drawn came to be (exist)."