OD&D and it's supplements were produced in digest format. In addition many of the products created for the Old School Renaissance are also produced in digest form. Chgowiz in this post (thanks Philip) mentioned that this paper mache book shaped box made for excellent storage of these digest sized books. Unfortunately the on-line site had it not available for months. I finally scored a pair when I went Christmas Eve shopping and came across them in a large Jo-ann store in Peoria Arizona.
Determined to some find some that the rest of you can buy I put my google fu to work and came across this website at CreateForLess.com. The only problem is that you have to order 3 sizes at once.
If you search for yourself the key term is Paper Mache Book Box. Also if you happen to find a rectangular box of the right size (6" by 9") then probably a lot of folks would be interested in that as well.
The Original D&D Discussion Forum has a lot of useful advice here.
And the post by Coffee which the true origin of this particular quest of mine.
Review of Wolf Hall, Episode 4: Devil’s Spit
6 hours ago