"Those people feel they've had a hand in saving something very valuable."
In the half-decade since Â£390,000 was raised to buy the Grade II* listed complex, staving off a plan to turn it into yet more student flats, the site has become a haven for small businesses including jewellers, a guitar-maker, a gin distillery and knifemakers, continuing the tradition of a place where stainless steel was first used on a commercial basis.
A specialist is painstakingly fixing the leaky roof and volunteers are leading a programme of other renovations at Portland, which dates from 1879. A set of handsome red-brick blocks, set around a courtyard off Randall Street, Highfield, it is one of the last remaining working examples of a purpose-built metal trades factory, a status that encouraged the Heritage Lottery Fund to approve a grant of about Â£100,000 for the repairs. A small amount of this money also went towards employing Stella, a former history teacher, as an education and outreach officer.
"I'm trying to show more people what happens here," says Stella, who feels those living near the site close to Bramall Lane, must be included in its activities to a greater degree. "We have a community within the works, with all the makers, but there is also the local community, and the wider Sheffield community."
The building became increasingly run-down until, nine years ago, the landlord put in an application to convert it into student accommodation. The proposal caused alarm among supporters, who mounted a fundraising drive to make the purchase in 2013 through a social enterprise comprising more than 500 shareholders. A charity, Friends of Portland Works, was formed to generate more investment, and a clear mission for the future was devised - to conserve the site's past, realise its potential as a heritage resource and to back start-ups, small-scale manufacturers and creative enterprises.
Good progress has been made with the new roof - several blocks have been completed, says Stella, and attention has now turned to the forge, a 'significant part' of the old factory.
"It's original, there's still a person who does hot metal drawing, and there's still a drop hammer here, which again is quite unusual."
There were 'a few glum faces' when the forge's roof was examined more closely. This section had not been touched since the 19th century, when entrepreneur Robert Mosley founded the works to bring together self-employed craftsmen - 'Little Mesters' with specific skills - who had traditionally been scattered across the city.
Rafters have split and the brickwork separating them is crumbling, says Stella. "Obviously it's a forge, so it's subject to quite a lot of heat. The repairs are going to be a lot more extensive than had been thought. It's an urgent piece of work."
Things can't be rushed, however. "It's Grade II* listed, which means everything has to be done sympathetically, and permission has to be granted for certain things as well. That takes a long time, it's not a quick process."
A band of around 15 to 20 volunteers, mostly retired people, assist with repointing windows, laying bricks and other tasks, and more helpers are sought. "Five years down the line that group is getting older. They can't do it forever."
Over eight months it took 2,000 hours of supporters' time, Stella reckons, to create Portland's MakerSpace, a room that can be hired out for events, exhibitions and workshops. "To see the work they've done is amazing. The works wouldn't be here if not for volunteers."
Larger rooms have been divided into compact units for tenants. "We get lots of enquiries for ground floor space," says Stella. "The income from the tenants is what keeps it alive. They just love the feel of the place."
The very qualities that give Portland its appeal - a utilitarian, industrial style - are the same that would have appealed to a property developer, she observes.
"Sheffield lost a lot of things during the war and we don't have that many original buildings. You can't get rid of everything."
On Friday, June 22, there is a chance to reflect and raise a toast to all that has been achieved. From 9.30am to midday in the MakerSpace a community coffee morning is happening as part of the national Great Get Together in memory of murdered MP Jo Cox; then, at 4.30pm, a fifth anniversary buffet will be served to tenants, shareholders, volunteers, friends group members and directors.
"I thought it was something worth doing as it's been a hard slog for all the volunteers and people who decided to save the building," Stella says.
And will there be 10th anniversary celebrations in another five years?
"I would very much hope so."
Visit www.portlandworks.co.uk for more information.