SKETCH-A-GRAPH

The Sketch-A-Graph had two expandable arms on a trellis-like arrangement; One arm held a pen and the other a plastic pointer. You moved the pointer and traced out a drawing, and the pencil moved likewise. 

You could magnify or reduce the resulting drawing by changing where on the concertina-like trellis you connected the arms and pointer.

I had one of these and it was impossible to use due to the Flimsy 70's plastic design which meant the trellis often fell to pieces and had to be held together with yards of Sellotape, and the fact that the suction cup thingy would never attach itself to the table properly, needing nine inch nails to hold the thing onto your mothers favourite antique dining table!

K-Tel sold an identical item as the "E-Z Tracer".