I don't have a good name (I wouldn't go too crazy trying to be creative. In that business descriptive is more the norm), but I would leave the word "artisan" out of it unless he is specializing in "handcrafted" renovation. It has a certain hippie-ish connotation that might make a certain type of customer go the other way. Then again, is he custom painting murals or frescoes? That sounds "artisanal". Think of the products people imagine when you say "artisan". Certain fancy breads. A guy who carves pipes from raw wood with old-timey faces on them. Wine and cheese. Stuff like that. I would never think of someone doing mechanical or electronics.
examples from Merriam-Webster:
They sell rugs made by local artisans or
we visited a re-created 19th-century New England village that features an array of artisans—a cooper, a carpenter, a blacksmith, a potter, a glassblower
I would maybe use the word renovation or restoration combined with his last name. This would attract people needing a wide variety of services, I think. Good luck!