Sorry in advance for so little information. I have been trying to recall titles/publisher so I could find copies of this (or better yet a web site devoted to it).
In high schools in California in the late 1960s, early 1970s there was a series of reading books for the kids. They featured recurring characters: male and female kids. The kids were always putting on plays and building things. I recall specifically: they built a space ship (out of plywood) big enough for themselves to play in. And I think one of them freaked the others out by pretending to be an alien. I think the kid wore an ant-head costume that was leftover from a production they did of “The Grasshopper and the Ants.”
Ring a bell?