Plasmid tubes holder for storage box

I designed this holder to fit in storage boxes. We use it to store small plasmid tubes in our lab.
The bottom is tight enough to keep the tube in place, but wide enough to require little effort in order to get the tubes back.
The raw and column annotations help a lot to be sure of the right orientation of the box when you open it (despite the box cover sometimes rotated).
No support required at all.