This is a storage caddy for the lightweight AMS riser (https://makerworld.com/en/models/64902#profileId-68560). It is designed to work with the associated plate holder (https://makerworld.com/en/models/107641#profileId-114955).

After designing this, I realized I can't use the screw holes closer to the front of the machine because they would be in the way when venting the glass. Subsequently, you can really only use the back two holes (possibly three) to secure this to the riser. This still works for my purpose, but the design could be improved.

I've only tested this with screwing it into the rear plate holder in the link above. It uses countersunk screws to not protrude into the container. I used M4x20 screws, but they should probably be shorter even though they worked.

I've included the Fusion 360, step, and stl files. Feel free to improve or modify the design.