Requirements
Essential Experiment Results
Documentation of results from essential experiments that prove feasibility
Key In-Sourcing plans
Key items (data, parts, code, infrastructure, etc.) that are needed from external organizations
Preliminary BOM and Manufacturing-QMS Plan
A preliminary bill of materials (BOM) and plan for manufacturing as well as quality assurance. What will be done in-house, what will be outsourced and how will you ensure quality?
Product Requirement Document (PRD)
A description of what the desired product should be capable of doing - avoiding how the product will actually do it - that comes later.
Provisional IP filing and formal FTO review
A provisional patent application filed with the US Patent office or equivalent agency in another country with a study of prior art and assessemt of the freedom to operate (FTO)
Works-Like and Looks-Like Prototypes
A prototype that works like the proposed solution, with all the key functions, but not necessarily in the final form along with experimental data documenting the performance