There are forty or fifty books on my shelves I’d consider indispensable (the Janet Arnold series, but I’d have to sacrifice someone’s first-born male child to replace them); these are the ones I pull out most often for my own reference or to wave at people.
Listed more or less in order of recommendations.
The Triumph of Individual Style Carla Mason Mathis and Helen Villa Connor
– Top slot by a considerable margin. Each of six sections alone (and there are more) would be worth the investment.
The Entrepreneur’s Guide to Sewn Product Manufacturing Kathleen Fasanella
– Not a sewing book. Clients wanting to start a line must demonstrate willing by investing in this one.
How to Make Men’s Clothes Jane Rhinehart
– More important than the info (which is excellent) is the mindset/philosophy of the traditional tailor.
Patterns from Finished Clothes Tracy Doyle
– There are other good sources for the industrial technique of making a rub-off without destroying the garment (counter-intuitively, the worst thing you can do to copy a garment is to take the seams apart).
Claire Shaeffer’s Fabric Sewing Guide
– …and a dozen or more of hers, primarily on couture techniques.
Recipes for Art and Craft Materials
– Every teacher needs this: salt clay (a.k.a. homemade Play-Doh), papier-mâché, modeling compounds, finger paint.
The Complete Book of Stuffedwork Toni Scott
– Theory and practice of soft sculpture.
The Art of Manipulating Fabric Colette Wolffe
– Related thematically to Toni’s book; what to do with design ease in sewn garments (mostly).
Patternmaking for Fashion Design and Draping for Apparel Design Helen Joseph Armstrong
– Students have complained that the illustrations are dated. Hey, pleats in sewn cloth are pleats in sewn cloth. Here’s what you need to add them (and everything else).
Vionnet Betty Kirke
– The bible for working with bias.
Bodymapping Kathy Illian (added later, no photo)
– the best book on building patterns on an actual body that I’ve found.
Last but far from least:
Sewing with Nancy, books and videos by Nancy Zieman.
Incomplete video list with notes
I used to recommend picking these up at your local library (or via interlibrary loan) but that’s become more difficult with everything moving to the internet and our book repositories “de-accessioning” so much. Worth a shot, though. Or I’ll happily blather at more length.