How to auto blink

In MMD, you can use randomly register blinking if the model has “まばたき (blink)” morph. It will register keys to blink morph so you can copy & paste to other morphs.

I think you can generate different blink animation if you delete blink keyframes and do it again.

For eye rotations (and more customizable blink), I think you can use F-Curve modifiers in Blender. This is auto blink in Graph Editor.

Noise: randomness, Function: for moving graph up&down, Limit: clamp to 0.0-1.0 (for controlling morph)

reference: https://blog.tenp-kukan.com/8453/