On 26/05/2017 12:17, NY wrote:

A bit of experience with Meccano would help a great deal, to understand
the importance of diagonal cross-bracing of a rectangular shape (eg the
gate in one of the questions) or to understand meshing of a train of
gears. Sadly modern children don't seem to "play" with Meccano any more.
I use the word "play" in its widest sense to mean build things and work
out by trial and error what is good and what is bad and how to improve
what is bad.

Lego Technic offers the same opportunity.