This stencil can be used in biology class or perhaps in medication schools when dealing with cardiac anatomy. You can get perfect drawings every time and label the names of each part. 

They are 5mm thick and 0.8mm thick. 5mm thick can be used as a card or a keychain, and 0.8mm thick can be used as a template because it is easier to draw with. 

If you are printing the file with bed adhesion, please remove those small pins after printing. (The third image)