Free printable eyelash ruler. Using a printable DIY eyelash extension ruler is an easy and effective way to measure your lashes. Here's how to use it: Download and print the DIY eyelash extension ruler on an A4 sheet of paper. Cut out the ruler along the black lines. Place the ruler on your eyelid, aligning the curved edge with the base of your lashes. Use a mirror or ask a friend to carefully pencil or eyeliner mark your lashes' lengths on the ruler. Mark along the ruler from the inner to the outer corner of your eye. Once all the lash lengths have been marked, you can use the ruler as a guide when choosing your lashes and designing your own personalised lash maps. Give it a try and see the difference it can make in your DIY lash extension application! **Be sure to print on A4 paper and do not scale or change settings.**