I just drilled holes in my new Iris container with a drill and a small size wood bit. I think it was for wood... Soldering irons are good too, and multipurpose I just made sure the drill was up to a good speed, then made a hole, otherwise, if it's not going fast enough and you push too hard, it will make small cracks around the holes. A soldering iron would probably be better but we don't have one so I just made do.