You'll have to pick a niche, understand it, build something, and then sell it. I think it's unlikely that a forklift dealer would want to pay the cost of a one-off custom system. I once was talking with such a business, their technology was antique and they knew they needed to modernize but viewed my $80,000 quote for custom software as too expensive. I considered pitching them on the idea of building it and then licensing it to them, as long as I could keep the rights to license it to other similar businesses. At the time I decided not to pursue it at all, but that may be an approach to take with small businesses that can't afford to pay outright for custom software or systems.