This plush toy is intended to have three different coloured fabrics, one for the upper body, one for the belly, and a smaller piece for the mouth. If you don’t wish to purchase additional fabric just for the mouth, it’s a small enough piece that you can likely use a scrap from the upper body or belly fabric.
Hi is designed for faux fur fabric, which most plush toys are made from, but you could also use polar fleece, felt, denim, corduroy, or anything moderately heavy. Lightweight or drapey fabrics may not hold Hi’s shape well when stuffed. Fabrics with a two-way stretch will work better than wovens, the stretch should be perpendicular to the grainline.
The teeth edges are left raw, so should be made from a fabric that does not unravel such as felt.
Since this is a plush toy, it will need to be stuffed with material. Most of the time you’ll want to use polyester fiberfill (polyfill), but if you have a lot of fabric scraps, you can use shredded scrap fabric. However this may be heavier and less soft than fiberfill. It’s also worth thinking about whether your Hi may be at risk of getting dirty, or want to go for a swim, as not all stuffing options are washable.