I got mine at hobby lobby. But I had to get 1/2" fake fur because that's the longest they had. I cut a long string fold it in half and stitch it up like a sock. Invert it so the fur is on the outside. To increase the gap and because the fur is so short, I've had to do 3 layers using this method. But it's very windy here during a fair portion of the year. Mine are shotgun style mics so I keep the seems on top or beneath. I figure that there's no desired sounds coming from those directions in the first place. I always keep the foams as a base, at a minimum it keeps the fur which will likely shed a bit from getting on the important parts of the mic. I use velcro cord ties (for computer cables) to cinch up the back end. And to wrap around the mic clip so they don't inadvertently slide off.
Ideally I'd like a basket style rig. If it rains, it keeps wet cloth that much further from your mic. And the sound source of the pitter patter of rain further away to dampen it's balance in the mix. Which is my main motivation for DIY fake fur as once they've been spoiled, they're mostly disposable. I bought a full yard for $20-ish and only used about 1/4th of it. If I ever get around to the basket / shockmount DIY version I'll need most of the rest, if not more. Plus it's a stylish leopard print.