Where did you find the material?
Local Fabric shop.
When I first did the boat seats i did a lot of googling and youtubing to learn. The basics are quite simple, which a cover really is pretty basic, so would plugs, in terms of its not intricate- we aren't making wedding dress with all sorts of fancy stitching and such. One thing that was suggested was for heavy material to buy an OLD machine, pre 60's where they are all metal, if ones not going to invest in a commercial machine. I got mine for $25 at a local thrift shop, its literally from 1920! Owners manual brags "The ease of sewing with electricity"lol. The nice thing is with a machine that old, it still has an "inertia wheel" So for curves or tight spots I can spin it by hand and go real slow being I'm not a seasoned ace...
Mine, I bought 4 yards each of a jacket liner material, kind of silky with a light insulation on back, then a layer of Thinsulate, and for a shell a nylon back pack type material... I used some real cheap blankets to lay over the plane and used pins and markers to make a pattern, stitched it up, went and fitted it, adjusted some lines a time or two. Then cut it apart for my pattern for finished product.
In the end I will have an insulated cowl cover, as well as prop and spinner covers for about $125... To buy insulated versions from Bruce's would be $600+... For me and my little rig thats 25 hours worth of Avgas! Plus too crappy to fly much so I've been sitting at night at the dining room table watching TV sewing away. I'll post ya some pics. If you are interested in biting it off, I'd give you any advice you need- though its coming from a novice thats figuring it out as I go