I did this exercise in Illustrator. First, I did the key with the ellipse tool, the rounded rectangle tool and the start tool. I used the pathfinder to add and also subtrat. I used the filter-styleze to drop a shadow to the key. Then I copy and paste the original to add a start and then use the pathfinder to subtrated.
The second one, I used the star tool and the ellipse, add color to it and subtracted with the pathfinder. The third one I use the the polygon tool with the start tool and then pathfinder subtracted.