I used to have one and my daughter had one - don't ask me where it is now, but it brings back lots of fun memories. Fiddling with the knobs, trying to get smooth curves, and the sound of the sand when shook to start over again for the umpteenth time.
Try your hand at this virtual version you can find here:
In the meantime - I'm off to do some stitching and promise to post on my progress soon.
Wishing you all a good weekend,