Windows users are advised to install DevKit via Chocolatey:
cinst ruby.devkit
devkit-win takes DevKit binaries and wraps them in a basic MSI installer that adds several binaries, such as make, to PATH.
https://github.com/mcandre/devkit-win/blob/master/devkit-32-4.5.2-20111229-1559-sfx.msi?raw=true
Binaries - DevKit