trace over (something)
To copy an image by drawing on a transparent or translucent piece of paper placed on top of it. When I was a kid, I loved tracing over pictures of my favorite cartoon characters. I thought he had drawn an incredible portrait of me, but he had just traced over a photograph he'd printed out.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
trace over something
1. to draw over something lightly. Trace over the drawing to make it a little darker. I had to trace over it twice to make it visible.
2. to copy something by placing a thin sheet of paper over it and drawing an outline of the thing to be copied. Trace over this picture and then photocopy about ten copies for us all. This needs to be traced over again.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.