When my son was about three, I made him a set of building blocks out of beautiful hard maple in a range of sizes and shapes. He's a little old for that now, but I still have the blocks, a whole 5 gallon pail of them. I admit that I played with the blocks along side my son. But now I've found a set of blocks I want for myself. These are Cuboro Building Blocks, available from the Design Within Reach website. From the catalog:
First designed as an instructional game for Swiss schoolchildren, the Cuboro Standard Building Block Set (1979) has evolved into a labyrinth designing exercise for all ages, including those old enough to run a company. Configurable in infinite combinations, the weighted marbles travel and forge their own path through underground tracks and hidden passages.The upgrade here is that the 2" Beech wood cubes have grooves and holes in them to accommodate marbles. So you build your structure with the idea of allowing the marbles to disappear inside the blocks wind around and reappear at the bottom. I am totally into this. I hope my wife is reading this blog. I also hope she orders me a set for Christmas without noticing the price ($275).