Vertex to Vertex snap

I need snap actor by arbitrary vertex (actor 1) to arbitrary vertex (actor 2) in viewport for design. Not pivot to vertex. How to do?
(mouse click on some vertex, hold and drag (snapping) to other arbitrary (other model) vertex in viewport).

if not how to design <not grid based> meshes?
pivot to vertex - is out of any use.

Seems like this is a complex way: first pivot vertex snap to some valid pos (MMB); after that snap actor by adjusted pivot.