It's Eddie! The tiny side character from Megaman, functioning as a tiny carrier for power-ups.
And he functions this way when printed, and has a hollow container inside, with room for an E-tank. The E-tanks come in four different variants, from decorative to functional ones, fitting SD cards and/or Nintendo Switch Cartridges (Just a heads up, I have not been able to test how well these cartridges fit, but I'm positive it should fit.)
The lid prints for itself and is snapped into place on the hinge. It might be a tough fit, if so, consider sanding or cutting a bit of the small hinges on the lid, so it will easier snap into place.
I hope he will print out nicely for you!