Basically cut some grooves into a dowel rod and use a rubber band to hold it down and pop it up when needed.
http://www.instructables.com/id/Rubber-Band-Powered-Bench-Dogs/?ALLSTEPS
Basically cut some grooves into a dowel rod and use a rubber band to hold it down and pop it up when needed.
http://www.instructables.com/id/Rubber-Band-Powered-Bench-Dogs/?ALLSTEPS