How to set model rotation exact to other part rotation?

I tried it so much times and it keeps spinning if i add code in loop or it gives wrong rotation and it set rotation of only 1 part in model. I need code that will get rotation of part and set model rotation exact to part rotation.

Do you mean for example part A's orientation = part B's orientation? This would be...

local ARotation = script.Parent.Orientation
game.Workspace.PartB.Orientation = ARotation