follow these instructions:plant a ghost brick,ctrl+numpad 0,build what you want to copy without using the brick gun.ctrl+numpad 0 again to stop the recording.
go to options,controls,and set playback macro to any key you want to use to playback you recording of what you built.plant the ghost brick you started with.
press the key you set to playback your macro.then you can watch yourself build without even touching the mouse or keyboard.