Is this for something like a large roll of film? I think light tight storage containers need a couple of things: a light trap or lip at the opening, and absolutely opaque material. Many plastics fail at the true opacity test (there are quite a few reports of things like 3D printed lensboards that leak in bright light). Especially if your material has extended red sensitivity; there are a lot of black plastics that transmit somewhat from just-beyond-visible to near-infrared. (In my line of work, "light leak from leaky opto-isolator" is very common.)
I think a metal cookie can or similar is one of the better options really, as long as you check the seams are fully soldered or glued shut. Store film in a black bag inside a metal tin, and tape around the outside of the lid so the lid doesn't pop off if you drop if. That's basically how 100-foot 35mm rolls are packaged. Also, you get to eat the cookies.