If you're on the Darkside, there's a metal shop on Soi Nern Plab Wan, at the intersection near Aqua Dymie bar.
I've used them for years, they've made my front gate & fixed a busted chair. If you visit and the shop is closed (the owner has a 2nd shop in the city) either call or visit the glass shop around the corner of the same building.
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