Similar concept to Tonino's suggestion, but refillable to give an unlimited colour range. They can also be used as dip brushes if required. Designed for calligraphy so they're perfectly shaped,and sharp tipped for accurate work. I use them filled with clear water to use with solid water colours or tubed poster paint on a pallet.
Also much cheaper, but with a week or so wait for delivery from Wish.com in China. Below is a direct link to the item, but you may have to register along the way to get there.
https://www.wish.com/search/paint%20...0c283303caa00e
PS: If you're new to Wish.com don't get too carried away with their silly prices, and don't forget to check the delivery charge.