When it comes for storage space it’s never enough. If you already have open shelves filled with some stuff but need to store some more you can make some by yourself under these shelves. All you need is some glass jars with metal lids and something to fasten them. That could be screws, nails, staples and even glue.
Remove labels from jars. Take the shelf you intend to use, lay it upside down, place all lids on it and fasten with something. Screw all jars into these lids and your space saving under shelf storage is done.