I found a clean copy of the October 1968 issue of Progressive Architecture over the weekend, and it had a story about architects designing for nomadic, mobile, flexible lifestyles, not just putting effort into immovable buildings.
An example was the Tank Chair, designed by Doug Michels and Bob Feild, who were working in Washington DC at the time.
Michels was on the cusp of forming the Ant Farm--his collaborator Chip Lord was also mentioned separately but prominently in this edition of PA.
The article says Michels and Feild put the Tank Chair into production, and that they were selling it "as a kit of prefabricated plywood parts to be assembled by the owner." Also, "It 'encourages owner manipulation,' the designers say, since it offers a range of 'paint options' and other opportunities for personalization."
Mhmm. Sounds to me like unfinished ply.
Also, it sounds like they only made two. There wasn't a picture, but Michels mentioned the Tank Chair in an interview in the catalogue for Berkeley's 2004 Ant Farm retrospective: "We found a quasi-abandoned house, built some furniture, tank chairs--one of which we gave to Jim Newman and one of which was eventually published on the cover od Domus magazine. Then I decided to move to San Francisco." [p.40]
Sure enough, the cover of the December 1968 Domus features a scrappy collage letter by Michels and Feilds: "Dear Domus, we have designed & are producing TANK/ROCKER would you like to publish it?"
Ahh, the good old days, when all a hippie needed to get on the cover of an international design magazine was a jigsaw and a dream.