I guess my first question is, why?

There is a roaring trade here in fitting out the million or so condos going up. Window treatments (decorative security screens, curtains, etc.) are a segment of that industry - buyers only get a raw space, which, IME (fitting out a few condos and apartments), is satisfied (mostly) by small, home-based owner-operators.

I could probably get several recommendations but it will be an exercise in futility (location, language, fabric, cost/price) and five days will be a massive challenge. Four weeks is not unusual, under normal circumstances.

If you are adventurous and have a day to kill head to Pahurat and walk around, looking for fabric and finishing shops. Have measurements on both English and metric, and hope for the best.

https://www.tour-bangkok-legacies.co...tle-india.html