I like to see what you are doing and read a little about the process. :)

Since you plan to make 81 blocks I assume you have them listed if only in your head and, since the ones I have seen in your store all appear to be convex (viewed from the outside of the block), I am wondering if you will, at some point, make a residential concave block (viewed from the inside of the block)?

I do not model, but I would think if a block = buildings along a street within a set overall diameter, then putting the street in the center with houses along both sides should fit within a two block length.  Maybe a cul-de-sac block and a tube block with no cross street between them / at the ends.  Bonus points if the cul-de-sac is big enough to put a gazebo on grass in the center, but that limits the houses on the end.

Just wondering. :D

http://en.wikipedia.org/wiki/File:Wellwyn_Garden_City_Cul-de-sac.jpg

http://en.wikipedia.org/wiki/File:Brookside_Close_-geograph.org.uk-_37506.jpg

Also, the street need not be straight.

http://en.wikipedia.org/wiki/File:Cul-de-sac80020_copy.jpg