Last year, he got interested in the idea of creating a "model adventure" layout featuring elevated Thomas tracks running around the living room. He tried over and over to get the tracks to hang together with supports under them, but they're just not built to do that. Peter taped a length of track to a 2X4, which Tom could then suspend between two piles of blocks - but the whole endeavor was very unsatisfying.
We tried interesting him other, more "appropriate" building materials - legos, Kn'ex, and so forth - but he couldn't wrap his brain around the idea that he was to use a blueprint to build the cool toy on the box. In fact, he couldn't even work out the process of connecting one K'nex to another (which, frankly, isn't as easy as it might be!). Instead, he squirreled away the little bits and pieces ... and over time it became clear that we were contributing at great expense to a pile o' junk.
But Tom continues to have an interest in engineering and building. We had given him a marble maze, which decided to build a full story high - and lean up against a wall. But that wasn't good enough. He wanted something bigger. His Dad, who is amazingly talented at going with the moment and inspiring perfect teachable moments, decided that now would be a great time to build that giant marble maze. We have dozens of cardboard tubes (long story), and together they designed and build a TWO-story high marble tube that starts at the old plastic maze, continues across the top of a wall (suspended by string on hooks) and then continues over the loft and down to the floor below.
In the first photo (below) you can see the tubes, connected by masking tape and suspended by string, running above the two windows in the loft.
This (below) is the looooong tube that runs from the loft down to the floor below. At the very bottom there's a bucket to catch the marbles. The bucket has a string attached, so the kids can haul the marbles back up. It's a big hit with visiting pals!