[JustPiper]

"We had finished the research stage and entered the development stage,"

'Entered ' being the key word for the naysayers to minimize the importance of this. 'Manufacture is a whole other game. What was developed? Any materials found besides verbal or even paper?

[donmeaker]

Technically, development means they were making the tooling. Development means that soft (wood or plastic) tooling is made and used to make sample parts. The sample parts are tested, and used to refine the plans for hard tooling.

This does not specify whether the parts made by soft tooling were good enough to actually use. The parts made by soft tooling would be made as well as they could be, but usually you learn something, so that is why you make the cheap soft tooling first, and modify that until the parts work. Then you make the hard metal tooling to a proven design.