PLS DO NOT DESTROY. it is too easy to make a pattern. Buy some contact paper, cut to rough size of the "flattened" part. Stick to to your t-shirt couple of times to weaken the stick. carefully wrap it onto the hand rest. trim off excess with exacto, including the holes. Ustick the pattern from the part, and stick onto stiff paper. Measure and add dimensions.
Now view the hand rest from the side, and measure the height, and width of the raised area. To estimate the bend radius, use a compass to make a series of small circles out of stiff paper, 1/8", 3/16" etc. Cut out and compare to the bend radius on the part. Incrementally zero in on the correct radius (of course, a set of radius gauges would be simpler)
There Ya Go. Fully dimensioned drawing, and Mother is Still in One Piece.