There is no minimum order quantity but it generally makes financial sense to mold at least 100 ea parts due to the time it takes to setup the mold.
The maximum quantity is determined by the quantity of parts that can be molded per hour. Single cavity prototype molds typically yield 30-60 parts per hour depending on part complexity. Protoshop runs two shifts per day so the maximum part yield would be on the order of 2,400 – 4,800 ea per week.