I guess today is cat day in Blockplay land. Though in both this and my earlier fischertechnik post, the constructions are supposed to be the primary subjects, I know there are some who will enjoy seeing Archie more than my projects - and will be demanding equal time for Webster!
The two larger models both use the full Froebel #6 sets, though there maybe substitutions, it has been a few days since I built them.
The smaller structure at lower left was built from a subset of the Froebel 6.
Having lots of different blocks to build with can be fun, and can be liberating. But it can also be intimidating. For younger children, and for those of us with developmental disabilities, whether they are full time limitations or intermittent periods of recovery from recurring autistic regression, it can be helpful to select at a subset with a limited number of blocks, of an even more limited number of types.
A very good sequence is the Froebel 4, followed by the Froebel 6, followed - in due time - by a little more variety.
All my best toys offer multiple levels of play: an easy level for regression periods, or for reentry after a period of neglect long enough to forget some of how to play with them, a medium level for regular use, and advanced level - partly for occasional bursts of enthusiasm, but mostly so I don't feel constrained at the intermediate level: I know I am there by choice.
I consider that one of the key secrets of Good Block Play.