Hello boys! Girls? Sorry, come back in 60 years and we’ll let you design and build Mars rovers. But it’s 1929 right now. No engineering toys for you.
Exclusion aside, thinking-toys for kids are good stuff. Erector sets were first sold in 1913. The company went into decline after the death of the founder in the 1960’s, and was bought by another company in 1990.
That $25 kit in 1929 dollars is close to $500 today!
Another ad, 1922,
I don’t know what specific set I played with as a kid, but I distinctly remember making a cool windmill, and then getting my finger caught in the electric motor’s gearbox.