The chairs' new owners -- all of them polio survivors -- crawl one by one to the three-wheeled machines with flip-flops on their hands, dragging atrophied, twisted legs and feet behind them.
One of them, James Goke, looks astonished to hear that on Friday Nigeria will not have had a case of polio in 12 months and as a result will be taken off the list of countries where the disease is endemic.
"Really?" said the 49-year-old, who trains young polio survivors in new skills such as carpentry, metalwork and weaving, to give them financial independence. "That's marvellous."
As in Afghanistan and Pakistan -- two countries that will remain on the list of endemic countries -- Nigeria's battle against the disease has been hit by years of violence and misinformation.
Vaccinators have been killed, warnings issued by some clerics that the jab was a Western plot to sterilise young Muslim girls and Boko Haram attacks have hindered immunisation drives in the remote northeast.
But through government campaigns, support from churches, mosques and massive funding from global charities, the tide has finally turned.
Dealing with the aftermath of the disease, Ayuba Gufwan works to improve the lives of Nigerian polio survivors who have had to cope with a lifetime of hardship in a society ill-adapted for the disabled.
At his workshop, 49 staff -- seven of them polio survivors like him -- and 17 young apprentices spend the day bending, sawing, bashing and welding metal.
On the concrete floor, thin sheets of steel are measured, mudguards are hammered into shape and frames are joined in an explosion of sparks.
Rubber inner tubes and tyres are added to a shiny mountain of chrome wheels. Red upholstery is stapled onto wooden boards to make seats.
The end product is a wheelchair designed to be easily maintained with all the parts replaceable in any village bicycle repair shop.
At 25,000 naira ($124, 114 euros) to make, they're given away free as long as the recipient is either at school, learning a trade or setting up a business.
"We presented our 10,000th wheelchair in October last year," Gufwan told AFP.
"We're now in the region of 11,000 wheelchairs, not counting all these in the workshop," he added.
In one room at the workshop, Habila Hasuna makes rudimentary prosthetic legs out of moulded rubber and chisels toes into a block of wood.
Some are for clients whose lower limbs have been amputated because of polio; others have lost legs to snakebites, road accidents or diabetes.
Increasingly, he works for those maimed by Boko Haram attacks across northern Nigeria or in Jos itself. Plaster of Paris casts for children and adults dry on a rack.
"There's a lot of demand," he said, thumbing through a folder full of measurements. His clients' hometowns are a roll call of the insurgency: Bauchi, Kaduna, Yola, Mubi, Gombe, Kano.
"Some hospitals refer them to us. If the person is desperate, they'll pay 5,000, 7,000 (naira). But hundreds have been free," he said.
Dream Come True
Gufwan described the 12 months since Nigeria's last case of polio as a "milestone" for the country and the world. Personally, it's a "dream come true", he said.
The 43-year-old contracted polio at age five but overcame losing the use of his legs to become a teacher and complete a law degree. This year, he sought election for the Plateau State parliament.
His aim was to improve disabled rights in the central Nigerian state and beyond, but he lost by just 700 votes.
The centre he set up in 1999 has received piecemeal funding over the years, including from Rotary International of which he is a member.
But largely it appears to survive on individual donations and enormous goodwill.
More consistent funding would help broaden the charity's reach, he said, but he has an unusual aim.
"By the time we have reached the very last polio survivor, we will shut down this place. But I don't know when that's going to be. I hope it's not such a long time," he said.
Shift in Focus
Gufwan warned against premature triumphalism on Friday and called for Nigeria to remain vigilant, continuing mass immunisation to prevent another generation from a life of unnecessary hardship.
"My number one expectation would be that emphasis would now shift from eradication to rehabilitating the polio victims," he said.
"They're here in their hundreds of thousands. We have them all over the northern part of the country particularly, and also in the south."
Out in the car park, James takes a test drive, turning the handles of the wheelchair, propelling it slowly forward.
It bounces over the uneven, rocky ground and a smile stretches across his face.
"This wheelchair is going to help us a very long way because of mobility," he said.
"Sometimes we would like to go to some places and this chair will really aid us to do this."
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