its not super flexible so your probably looking at combining a few piece to get the look you want inside the tank.
here's two links that have a few good ideas.
Good info! Just get the piece you want and cut it up. You can screw it back together in the tank. Some well placed screws can be hidden easily with plants, moss, rocks.... Manzi is the best wood for tank IMO. You don't want a flexible wood as it will be really soft and will fall apart in your tank.