You need identify your core business goals with the small production runs and if you don’t meet them what to do and if you do what to do next.
Your prototype must be designed specifically for a small production run and assembly.
The design differences between a small production run are variable depending on the product, however even subtle design changes will make the difference in many variables such as the products end surface finish to the products performance.
Read my response to for more detailed information: We have built a prototype of a WiFi speaker. What’s the best way to find a manufacturer that could produce a prototype ready for production, and a small number of these speakers?