Tina,
No, if you dry out that slip it will not be the best for workable clay. Casting slip is different from simply watering down clay. I would not advise it. Maybe there is a potter in town who has moulds or a ceramics shop that uses moulds that you could borrow. Or there are simple ways to make moulds for slip casting. Or sell it and use the money to purchase other materials. Good luck!
Mindy M.
Halifax, Nova Scotia, Canada