Building Myxer is trivial. Download this repository, Cargo, and libpulse-dev & libgtk-3-dev system libraries, and run cargo build --release in the root directory.
Major releases are available on the Releases page. If you want something more breaking edge, you can download an artifact of the latest commit here. These artifacts are untested, YMMV.
Call cargo run to build and run the application. If you have nodemon installed, you can call it on the root directory to automatically watch the source files for changes and recompile.