Founders prepare hard for the first investor meeting and then get caught by the second. The first conversation is about whether the problem is real. The second is about whether you have thought through the physical realities of shipping a product.
Bill of materials, and the path down
Nobody expects a prototype to hit its target cost. What they expect is a credible path: which line items dominate today, which of them fall with volume, and which are structural. Being able to name your three most expensive components and explain what happens to each at higher quantities is a strong signal.
How long does one installation take
For any device that attaches to existing equipment, install time is a business model input, not an engineering detail. An hour with basic tools opens a very different market from a half day requiring an electrician and downtime. Measure it honestly on your own prototype and quote the real number.
Who installs it
The follow-up question is who does that work. If the answer is your engineering team, your growth is limited by hiring. If the answer is the customer's own maintenance staff, or a channel partner, your product needs to be simple enough for that to be true.
Certification and where it bites
Expect questions about which approvals your target market requires, what they will cost and when in the schedule they land. You do not need certificates at the prototype stage, but you should know what applies and have designed with it in mind, since retrofitting compliance is expensive.
What happens when a unit fails in the field
Warranty, replacement logistics and diagnosis at a distance are unglamorous and they show operational maturity. Being able to say how you would identify a fault remotely and what a swap costs answers a question the investor is already asking themselves.
The underlying test
All of these questions probe the same thing: whether you understand that hardware businesses are constrained by physical operations, not just by product. Answering them plainly is more persuasive than any projection.