One more bit of trivia on oxygen scavengers. If the container is well sealed and there is enough oxygen in the container, a scavenger packet can sequester enough oxygen in the form of iron oxide such that a mild vacuum develops in the container. By capturing the O2 molecules which were in gaseous form and converting them to iron oxide in solid form, the volume of gas decreases which creates the partial vacuum. The more rigid the container, the more obvious the vacuum is when you break the seal and open the container. A rigid container with several oxygen scavengers in it and filled with pure oxygen before sealing would probably create a quite strong vacuum. That could be a neat thing to experiment with. You can buy oxygen scavenger packets online but once you open the vacuum sealed bag they come in, they have a limited time to use them unfortunately.