I have added, with permission, the full text of Kenneth Kawamura's 1977 booklet Geometrical Compound Origami or Meditations on a Waterbomb to my site at http://www.origamiheaven.com/historyindex.htm
This documents the modular discoveries of Kenneth and Joe Power during the early 1970s. The 6-piece skeletal octahedron had, of course, been discovered much earlier on, in about 1965, by both Robert E Neale and Kunihiko Kasahara. Dave