I had a good look around the internet before Nathaniel's birthday for some similar blocks, but unsurprisingly, they were few and far between and rather expensive.
So when the builders left us a great pile of off-cuts from the roof (intended for someone's wood burner), we were rather pleased. It may be soft wood, but there are some pretty brilliant shapes, and let's face it, I was never going to get around to identifying, buying, cutting and sanding wood.
Over the weekend, I got together with the sander (if I was a true Steiner parent, Nathaniel and I would have done this together, by hand, over many winter afternoons - but neither of us have that patience at the minute!), and finished off a pile of "windmill pieces" (so that's what we are going to be using them for!).
I am inordinately pleased!