After finish the Product Design, will need to make a rapid prototype to test . In the old way, it is normal way of CNC and vaccum molding. but not add some new ways to make (3D printing for plastic and metal, simple injecting molding ).
Some Advantage and Disadvantage of each way:
Machining Way
CNC
vacuum molding
3D Printing
simple injecting molding
Advantage
Good Strength and Quality
Good for small quantity
fast and difficult shape
lower cost and many types of material
Disadvantage
High Cost
less types of material
less strength for plastic
Need time to make mold