Here are some great button designs that makes the buttons looks like hand-drawn buttons, it was designed by Tiffany Rayside. There are six styles to choose from Lined, Dotted and Dashed in thick and thin styles.
If you are having trouble with the pen, try the archived copy on GitHub
Hand-Drawn Button Snippet
See the Pen Imperfect Buttons by Tiffany Rayside (@tmrDevelops) on CodePen.0