"We had to source some bits and pieces, and up until the last minute we weren't sure if it was going to come off," said Mr Pine.
The jet pack was "rocket technology, basically". But it wasn't a rocket with "flames shooting out" because it was powered by a chemical reaction at high speed.
"It's lifting him, and whichever way he points his body is where it goes," Mr Pine said.
Yesterday's flight was the first time Macomber had felt he was posing, as opposed to flying quickly," Mr Pine said. "[He said] it's like riding a bicycle. It's amazing how much control he has over it."
Macomber flew out over the water but couldn't muck around because he had only 20 seconds of air-time.
"You don't want to fly 11 seconds out," Mr Pine said, "because you'll end up wet."