In case this might be of interest to anyone:
Humble Bundle currently has a deal up for a bunch of books about costuming. They’re a mix of books focused on cosplay specifically and sewing in general, but I figure much of it would probably be relevant to anyone who likes to make DIY costuming for LARP. I have absolutely no idea of the actual quality of the books, though.
It’s only going for the next 20 days from today (28 May 2020), though, so if you think you know people who would be interested, it would probably be good to direct their attention to it via another medium if they don’t check Diatribe frequently.