FL does not have any law regulating the payment of that final paycheck. For the most part, FL has very few labor laws and no regulatory agency that enforces the few laws that might be on the books. If your former employee choose to do so, however, she probably could take you to small claims court for her final paycheck. I have no crystal ball as to how a FL judge would rule here.
Where you might get into trouble is if you withhold ALL of her final paycheck. You could then trip over Federal minimum wage law, which is enforced by the U.S. Dept. of Labor, Wage and Hour Divsision. USDOL-WH, however, won't get involved if you pay at least minimum wages and there is no issue of you owing her overtime pay. Also, USDOL-WH won't get involved unless someone complians to it.
Of course, you also need to make any required deductions for FICA, income taxes, etc.
I like DPH's suggestion but I suggest that you give her a deadline and if she fails to meet it, go to plan B. If she does NOT contact you and return the equipment, you probably could do what you suggest. Pay her minimum wages, withhold the rest (or the value of the unreturned equipment, if less that the total amount owed, less any required deductions, and hope she does not take you to small claims court.