Don’t let the simplicity of a gas block’s function fool you, it is possible to make a bad one. They must handle high gas pressures and extreme heat so using sub-par materials is out of the question. They also need to be machined to exacting standards, otherwise you run the risk of driving yourself bat-shit crazy because every roll pin you try to use ends up mushroomed and bent all to hell or worse yet, excessive leaks or blockages in the gas system.