Who would believe that the design below was constructed entirely with straight lines? If you find mathematical designs like this appealing, you might try to create some line art, also known as string art.
The basics of line art involve connecting dots along a vertical axis with a horizontal axis with a straight edge. The template below is actually 4 quadrants-worth of line art. 
A line art template created in MS Word can be accessed here. Once students get practice with line art, they can start experimenting with other shapes. For example, mark every centimeter on a regular polygon. Then connect the dots and you’re making line art designs!
Here are some helpful links for learning more about making line art:
Ms. Miles' Math Site 