This is a card divider for standard size TCGs with similar design and measurements as those made by Ultra PRO and Ultimate Guard. As such it should be compatible with most of their current accessories.

The model is oriented upside-down to get a nice finish on the front.

I have also provided a STEP file for customization.

If you are using older narrower deck boxes, check out https://www.printables.com/model/468836

Update

2024-02-28 Replace .f3d with .step