This is a wing nut or knob for a 1/4" threaded rod designed to comfortably fit fingers.
Since the model is fully parametric, the hole size can be adjusted to match your rod, or the number of finger holes can be adjusted, etc...
The model works well with 3, 4, and 5 wings. More wings would fit if the radius was increased or the finger hole decreased, etc.
Note that the hole is conical, a bit larger on the bottom to make threading it easy. The knob should self thread onto the rod.