Unfortunately, paper versions are currently very hard to obtain. The last reprint was in 2007 (Twist Origami 1-3, and Introduction to Creative Playing with Origami), and the volumes were too little to match growing interest. When starting this project a year ago, I already had most of the books, but getting those I didn't own was very difficult. The copy of Solid Origami I grabbed was - I believe - literally the last copy I could find on the English-speaking internet. I grabbed it from Kim's Crane (https://kimscrane.com/) and I think they had a copy or two of Fujimoto's other books at the time.

If there is an origami society in your country, they may have some of these books in their library (rules for lending may vary, of course).

These books being so difficult to find was one of the reasons I wanted to ask Fujimoto's heirs to release the books to the Public Domain.