@rais14 I made my bracelet with hand dyed rainbow DMC cotton perle from KreationKaos, she is US based and has an Etsy store. Shop drops are normally on Fridays. If you go to my profile you will find more photos of bracelets using.
@rais14 DMC coloris has a lot of multicoloured threads. you can check on the net where to find some DMC thread, sadly I live in Europe so I cannot help much more than this >.<
maybe Amzon, you can try to search for "Yokota Sashiko Thread 40m" or etsy too.
Or maybe in some stores, such as hobbylobby or other craft stores. I'm sorry i cannot help more =\
This bracelet was really fun to knot and in total took me way less than a day! I really enjoyed it and love they use of multi-colored string. I also love the straight edges technique! Would recommend! ❤️