The type of nuanced imagery that defines tattooing today requires more than just precision. Subtle shading may involve delivering ink to different levels of the skin in multiple passes, and doing so in a way that minimizes tissue trauma. Although dual-coil tattoo machines provide ideal ink application, they can be heavy and noisy, as well as generating significant vibration and skin damage. To address those drawbacks, designers have tried alternatives ranging from pneumatics to cammed servo motors. Ultimately, they realized that those formats have drawbacks as well, leaving room for innovation.