ActionPackers by Rubbermaid have worked for me for many years. I believe they have models within your parameters. They are durable, reasonably light (although one in your size range will be heavy when fully loaded), but not waterproof in the sense that they will not leak if fully immersed. I have used mine in wet environments (think surf landings) by duct taping around the lid. I have some that are more than ten years old that still work. They are not what I would call "cheap." but they are a good value. I have never been able to destroy one.

You might also look at military surplus. That is a good source for all kinds of unusual containers.
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Geezer in Chief