The Greek goalkeeper met staff and visitors when he performed the ribbon-cutting ceremony at Cotswold Trade and DIY Centre this week.
The new facility at Robson Avenue on Teesside Industrial Estate, Ingleby Barwick, stocks everything from workwear to power tools, door handles to tape measures.
The one-stop shop is an extension of doorset and doorkit supplier Cotswold Manufacturing, which has operated from the 82,000 sq ft site, for the last six years.
Ken Napper, who runs Cotswold Manufacturing with business partner Stuart Burnett, said: "We are delighted now that the trade centre is officially opened, it is a welcome extension to the business."
"The manufacturing side of the business is thriving, and this new retail facility means that local tradesmen and residents can source top quality tools and accessories right on their doorstep."
"We are also very grateful to Dimi for taking the time out of his busy schedule to come and perform our opening. The vast majority of staff, myself included, are all Boro fans so it was lovely to welcome him here."
After performing the opening ceremony, Dimi spent time chatting to fans, posing for photos and signing autographs.
He said: "I was very impressed with the whole set up at Cotswold Manufacturing, and I wish Ken, Stuart and all of the team every success for the future."
Suppliers attending the event included Carlisle Brass, DeWalt, Makita, Klingspor, Karcher and Reisser.
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