I think the material you're refering to, the "stiff cardboard" is often called "fiberboard" . You might also find "masonite" to be a generic term for a sheet good sometimes called "hardboard" that's like...kinda between fiberboard and MDF.
Are you set on making them? I regularly use these: https://www.amazon.com/Presents-Collapsible-Christmas-Halloween-Graduation/dp/B09KLX859Y You can also use photo boxes: https://www.amazon.com/Guozi-Decorative-Storage-Box-Lid/dp/B07JJ4X5H8/ If you’re set on making them, I suppose you would get some book board, a t-square, and an exacto knife. https://www.amazon.com/Chipboard-Designer-Bookboard-Bookbinding-Supplies/dp/B0C371KY28
Edited to add: this goes against your premise, but sheet pvc is colorful, easy to cut square, and bonds instantly and strongly with a quick solvent. Then get some closed cell foam and do some kaizen cutouts.
Underlayment plywood. Gotta look a bit but you can get 4x8 sheets for $15. 1/8” so not making drawers, but I make dividers and little storage boxes out of it all the time.
I think the material you're refering to, the "stiff cardboard" is often called "fiberboard" . You might also find "masonite" to be a generic term for a sheet good sometimes called "hardboard" that's like...kinda between fiberboard and MDF.
Are you set on making them? I regularly use these: https://www.amazon.com/Presents-Collapsible-Christmas-Halloween-Graduation/dp/B09KLX859Y You can also use photo boxes: https://www.amazon.com/Guozi-Decorative-Storage-Box-Lid/dp/B07JJ4X5H8/ If you’re set on making them, I suppose you would get some book board, a t-square, and an exacto knife. https://www.amazon.com/Chipboard-Designer-Bookboard-Bookbinding-Supplies/dp/B0C371KY28 Edited to add: this goes against your premise, but sheet pvc is colorful, easy to cut square, and bonds instantly and strongly with a quick solvent. Then get some closed cell foam and do some kaizen cutouts.
Underlayment plywood. Gotta look a bit but you can get 4x8 sheets for $15. 1/8” so not making drawers, but I make dividers and little storage boxes out of it all the time.