Define the use
Start with the products inside, their weight and the retail setting. Those details guide the bag structure and the reinforcement to review on a sample.
List the products the bag will carry, including their approximate size and weight. Consider whether several items may be packed together. This gives the structure, base and handle a clear job to do.
A bag carried through a shop, an event or a longer journey may need a different balance of presentation and strength. Note how it will be packed, handed over and carried.
A physical sample lets you review how the contents fit, how the base stands and how the handles feel when the bag is loaded.