I want some capsules that I want to fill with vitamin powder and just swallow them, any idea where to buy them in BKK

Chinese pharmacy, or a local wat may be able to direct you, some monks do up folk medicine, herbals.

Any pharmacy in Thailand either stocks them or can order some in a few days

There's an outfit called Sukondee that wiill be able to supply for you. I bought capsules from them a few months back, they're Thailand based and have a website you can find with Google.

I just use cigarette papers, roll them into a twist. Withstand humidity at least as good as gel caps.

asked in 3 pharmacies today, nothing, boots, local pharmacy and another branch, noting

the idea is not to keep them in cigarette paper, but to swallow them without tasting it