I thought of this a while back and am finally sharing the idea. You can make one based on looking at this video, but I will have plans with all the details and where to get all the parts soon. Please standby. These are surprisingly easy to make and very inexpensive. Eventually I might make a few for people that don't want to make them yourselves. Just let me know.
In the meantime, please watch the video, ask/ leave comments below. Or you can read more about this on my blog here: http://www.glassetchingsecrets.com/blog/sandblasting-foot-switch-free/