Where can I find very sturdy but not too thick of book board? : r/bookbinding

5-in-1 Book Cover Guide to Create Sturdy Chipboard Covers

20 Pcs Book Board, 80PT 0.086'' Thick Binders Board

Build a Sturdy Notebook with Coptic Book Binding

We R Cinch Book Board 8.5X11 2/Pkg-Gray Chipboard

Complete Bookbinding Kit Make Your Own Journal Book With Supplies

Perfect Bound Book Printing

Children's Board Book, Part 1

10 Tips for Measuring and Cutting Book Board

Complete Guide To Perfect Bound Book Binding + 5 Great Publishers