You can use nearly any type of fibers and yarns to make fun and beautiful things with the Loome tool, here's a recommendation on what weight or thickness of yarn is best. Experimenting is key, see what you like. You can also download the chart.
WHERE TO BUY MATERIALS
Local Yarn Stores (LYS): Great for a range of indie dyed and commercial yarns.
Online: Purl SoHo: Wide range of premium yarns and threads.
Online: WEBS: Large selection of natural and quality yarns. One of the largest online and retail yarn shop.
Online: Etsy: Handmade and unique materials (beads, ceramics, charms, driftwood, leather, metal closures, yarn, etc.)
Online: Knit Picks: Wide range of affordable, great color yarns.
Online: Darn Good Yarn: Ethical and recycled yarns (recycled sari and t-shirt, denim, vegan, llama, banana fiber, hemp, linen and nettle yarn).
Community: Fibre Share: Quarterly yarn share and swap.
BEST SCISSORS FOR POM POM MAKING
One of our most frequently asked questions is what's the best scissors for serious pom pom making. We recommend 1) Singer Professional Series ($17, available on our site) or 2) Westcott 7" or 8" Titanium (approximately $14).