Designed for the Cards Lair Pro 1000. Should fit any of this kind of style deck box, though, really. Dimensions are roughly the same (A couple of millimetres smaller width/depth than the inserts for the Ultimate Guard Flip'n'Trays, but a little taller than them to clear the brim of the cards lair).

Specifically designed and made for these, though:

https://www.gamegenic.com/product/cards-lair-pro/?attribute_pa_color=gray-red

Printed at 200% speed on an Elegoo Neptune 4 with generic PLA. No supports used.

It might be worth noting that I removed sharp corners and edges with a light sanding post-print. I did a little de-bur to clean up the underside of the top handle, due to printing without supports.

NOTE: These boxes will need some light sanding on each face in order to fit. They've been purposely designed to be a fraction of a millimetre too big, as I like the sanded look. Print at 99% scale if it isn't your thing. (Not tested, the inside tolerances for cards is fairly tight).