Most of the stuff I used I had on hand except a DHT11 humidity and temperature sensor module that I got as the first purchase of the new year.
I reused an Adafruit Flora arduino board, a short length of neopixel strip and a neopixel ring.
I had some leftover white microfleece fabric which I used for the scarf. Anything soft in a light solid color will do.
The finished width of the scarf is about 6 inches wide and the length around 6 feet long.
You will need a small bit of fiberfill batting to diffuse the neopixels or just use a layer of the microfleece.
For the diffuser and neopixel pockets, use something like a muslin or thin light fabric.
You can make the scarf all with a regular sewing machine. I also use a serger as I find that it is useful for straight seams that can be sewn and trimmed at the same time.