e.g. to "copy" another objects x coordinate onto the current object without also moving the current object in Y or Z: 1. put the cursor on the desired X coord 2. select the object you want to move 3. change rotation/scaling pivot to "3d cursor" (period key) 4. turn on "move object centres only" 5. scale in x (s key, then x key to restrict to x) 6. type 0 and hit enter