pantograph
noun
°A mechanical linkage based on parallelograms causing two objects to move in parallel; notably as a drawing aid.
"''A pantograph can be adjusted to make either scale - or exact copies."
°A pattern printed on a document to reduce the ease of photocopying.
"''I was impressed by the quality of the pantograph; I hadn't noticed it on the original, but the copies were covered in unpleasant lines."