In the thermoforming process machining is critically important. I guess the best way to think about this is, in the higher volume context people are familiar with the process called injection molding. Where a mold closes a molten plastic is injected into the mold, the mold opens, the part comes out completed.
Below is The Transcribed Video:
What is a challenge with injection molding is the tooling is often very expensive and the run quantities are often very high because there is a large setup cost. So in thermoforming we can make parts of similar complexity but at much lower volumes, but it is done through stages.
If you think of this part, this was first formed. So you are looking at a raw form part where we are starting to get features, in this sense this is the surface that will interface with the lid and a recess for a light, but otherwise this is not yet functional.
After this stage we move onto the next stage where you can see holes for fasteners, the front lights have now been opened, and the part has been cut down here to facilitate mounting onto the unit which then ultimately, in the final assembly this part has been painted its referencing its framework and you can see how there are very few seams which ultimately ends a nice clean design.