You don't sell to your customers in those industries - you sell to the industry associations from whom your customers get operational/industry advice. Partner with them to promote your product to the customers.

The key is to remember that you're an Outsider, an unknown quantity, and so you present an inherent risk from the outset (especially in the genAI field, which brings a lot of additional suspicion all on its own). What you need is an advocate who is already established and respected in the industry you're targeting. That gives you a bit of "social proof".

You have one customer... assuming that they are happy with your offerings, perhaps you can get them to be your advocate? Offer them a great deal in exchange for being able to use their name in marketing materials, to get them to write up an article about your product in a trade journal, to talk you up at trade shows, etc.

I might be giving my age away, but it’s like we’re back in the days of fax machines and Rolodexes. Most of the industrial suppliers and ops folks we talk to aren’t hanging out on LinkedIn or tech forums. They trust face-to-face chats, trade magazines, and the vendors they’ve known for years. Cold emails go nowhere, old-school phone calls or even showing up in person actually work better. These buyers move slower, want to see you’re serious, and often need help understanding what the tech even does. So we’ve had to meet them where they are, usually offline.

Congrats on the first sale,that’s huge! Legacy industries are brutal because you’re not just selling tech; you’re selling a behavior change. A few things that worked for me in similar spaces:

Trade magazines & physical mailers (seriously). Decision-makers in these industries often ignore digital noise but read industry pubs. A well-placed ad or "How Similar Company Cut Costs by 30%" case study can land meetings.

Embed yourself in their language. One client doubled replies by swapping "AI agent" with "24/7 digital foreman" in outreach terms that resonate with their mental models.

Leverage your first customer. Film a 90-second testimonial (phone video is fine) of them saying "I was skeptical, but…"use it as your #1 outreach asset.

If you’d like, I’d be happy to audit your messaging for free. I’ve helped other hardware/AI hybrids reframe their pitch to cut through the skepticism (e.g., one company replaced their ‘dashboard’ with a ‘command center’ and saw a 40% bump in demos). No strings just hate seeing solid tech get stuck in positioning purgatory!

My 0.02c

- carry out some deep market research and analysis, work out the best niches, garner insights into buyer behavior

- content marketing still works but if you use AI effectively becomes extremely efficient and powerful. For example, you could build an MCP server that gives you superpowers with keyword research and SERP analysis tools. There's a growing body of knowledge in this area, sometimes called vibe marketing

Not even remotely an expert and this advice is from second hand knowledge.

Hold in there. Sales cycles are long. Figure out conferences where people go to. Go there. Drop into offices and ask for their time. Find out people who know people.

What did you do different, from getting your first customer (which was successful) to getting the second now? Either way, keep creating value for that first customer, that'll be much insightful

Find people willing to help on the sales team of your first customer. They will have way more experience and established networks into the rest of the ecosystem.

How did you find this niche?

My rule of thumb is a problem presents its own solution. But I’m not sure how it applies to you without knowing more about your product.

Have you looked into tradeshows? My company (large industrial equipment) still heavily does them. My company is not sold on AI, so stick to a quick demo of it's utility and stay away from 'buzz words' when talking to them. When I bring up 'Agent Mode' people roll their eyes and what we do is mostly software these days! Target the young people in those companies who are frustrated but haven't bailed yet. If it works and people can see it they'll buy in if it saves them time. Especially in the world of 'we can cut 10% of a workforce and still ship products'. Best of luck! Open invitation to reply with a link or repo!

Ask your first customer for referrals.

Build another product.

Microsoft didn't stop with basic.

Diversify.

There is no rulebook.

Good luck.