From selling chocolate bars at school to building AI for manufacturers
Casla Conversations with Andrew Longman, founder of Promptable Millie Hurst, 2nd March 2026
Andrew Longman was the kid who sold chocolate out of his school bag - until a teacher caught him and confiscated the lot. Two decades later, he's still solving problems, gaining loyal customers and selling things, only now it's AI-powered documentation software for manufacturers.
The path between those two points hasn't been a straight line. There have been failed apps, bedroom startups, multiple pivots, and a six-month mentorship that changed everything. But what's stayed consistent is Andrew's instinct to spot a problem and try to fix it.
'Some people tell me it's taken me ages to set up my own company,' he says. 'Others say it'd be weird if I'd got it right the first time.'
The problem worth solving
Poor documentation costs manufacturers real money. Internal processes get confused, knowledge walks out the door with experienced staff, rework piles up, and compliance slips. According to Andrew, the cost of poor document quality can run to around 3% of a manufacturer's revenue.
'So if you're a £10 million manufacturer, that can be up to £300,000 a year that you're losing because of poor documentation quality,' he explains. 'It's costing you a tangible amount of cash every year that you could claim back if you managed it better.'
That's the problem Promptable was built to solve. It's a live, AI-powered manual - a system that sits inside a manufacturer's operations and keeps their documentation accurate, accessible and useful. There's a chatbot layer on top, but most of the work is happening in the background: AI doing the heavy lifting so that teams can focus on making things.
It's a compelling pitch, but getting there took years of learning what not to do first.
Building, failing and building again
While studying aerospace engineering at the University of Sheffield, Andrew caught the startup bug. His first venture was a recipe-sharing app. 'It was social media for food, essentially,' says Andrew. ‘I didn’t get anywhere with it.’
But the experience taught him something important. He realised he didn't want to go and work for a big organisation and relocate to Rochester or Derby - he wanted to build something on his own terms.
'I'd got the bug. I just had to set up my own business.'
What followed was a not particularly glamorous process of experimentation. He looked at the problems right in front of him and noticed that student societies struggled to get their training kit printed, so he started a printing business out of his bedroom. That company, Stash Society, is still taking orders today - ticking away in the background while Andrew focuses on Promptable.
He then taught himself web development online, worked through AI textbooks, and talked to as many people as he possibly could. But the biggest shift was learning to start with the problem rather than the technology.
'I spent a lot of time holed up in a bedroom writing code, thinking I was building interesting things, but I wasn't actually solving any real problems,' he admits. 'Now I spend a lot of time having interesting conversations instead. That's been the biggest turning point for me.'
The turning point: finding a co-founder
The other turning point was meeting his mentor and co-founder Chris Muscroft, and forming a partnership that would instil a new kind of discipline and focus.
'It took three months of us sitting down face to face every week, asking ourselves: what is it that we're actually selling? What problems can we solve with this technology right now?' Andrew tell us. 'We had the tech and the ideas, but bringing it back to tangible value for people in our network - that's when we started getting somewhere.'
Today, Promptable has pilot customers - smaller manufacturers in Sheffield and Catcliffe, with more in the pipeline. They've also launched a partner network for sharing insights about practical AI in manufacturing, and their version two product has recently gone live with video demos for potential customers.
It's still a small and fairly bootstrapped team, and Andrew is honest about the challenge of balancing product development with content creation and sales conversations. But the foundations feel different this time.
Switching off
We asked Andrew what he does to decompress, and the answer was immediate: he cooks.
'If you don't switch off, you can't function outside of work, and I don't think you can function inside it very well either,' he laughs. 'If I can finish work and just cook something nice, that's ideal.'
Beyond the kitchen, his perfect weekend involves coffee in Sharrowvale, a walk out into the Peaks, time with friends, and a pale ale.
Quick-fire
A tool you can't live without? Claude Code - the command-line coding tool from Anthropic.
What do people misunderstand about your work? 'Most people know AI as ChatGPT. We're a practical application where AI works in the background doing tasks for you. Some of the manufacturers we work with still do everything with pen and paper - we're trying to sell them the frontier of technology. There's a gap to fill in terms of understanding and education.'