Me. I couldn't source a decent case to fit a Jag SS.
I used a nylon dog blanket the dog had torn a hole in, but you could use a new one.
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I'm not joking. I don't think anyone produces material specifically for lining guitar cases, they just use a range of other materials, e.g. as used for soft toys. If you want the 'short fake fur' type of lining it is available off the roll but for the quantities needed for a guitar case a small throw or blanket is possibly the cheapest solution.
It looks good (it was a candy apple red dog blanket) and works well (IMHO):
The case is 12mm planed softwood strips and two sheets cut from 3mm MDF. If I was doing it again I would cover in proper Tolex-type vinyl, the one I chose is a lovely colour but easily scratched.