I've just been looking at a range of space toys called Space Movers on eBay. They appear to be cheap but inventive plastic vehicles made to take three half inch action figures common at the time. Figures mentioned on the boxes are Star Wars, GI Joe and Marvel Super Heroes. The toys are by Echo Toys from 1983.
This struck me as rather clever and presumably avoided any nasty legal action from the likes of Kenner. If only they had stuck to just mentioning the action figures on the boxes, but alas they appear to picture Star Wars figures on the box, which might have been a light sabre too far.
The idea of knockoff equipment for figures wasn't possible with Project Sword or Spacex. For a start there were no figures and nowhere to put action figures of any size, not even the HO golden astronauts that came with the Triang line (there was the spacex moon base though).
Did any toy line in the Sixties offer vehicles in which other brands' figures could go? Major Matt? Action Man?