p3ter-dev/custom_WAS ? reverse-engineered prompt

Build me the Rust project in the custom_was folder into a clean, working starter app or library that actually runs and is easy to extend.

I do not have any existing docs, so please make sensible choices from scratch, keep the code simple, and give me a good project structure with a clear entry point, basic error handling, and a few example tests if that makes sense. I want it to feel like a real usable foundation, not just empty scaffolding.

If there are any current Rust best practices or crate docs that would help, look them up online and use them. Also include a short README that explains what it does, how to run it, and how to test it.