I have several items that would be very hard to extimate shipping cost. Therefore, I'd like to display a message when the item is overweight and requires special shipping method.

How can I add a message that it will auto appear when a product(s) is overweight, such as:

Your order requires special shipping and handling due to weight or item restrictions, a customer service agent will contact you to discuss shipping options, your order will not be processed until it has been confirmed with a Customer Service Agent