Some of the people who have worked on DIYcity projects so far have proposed a set of loose design principles for building DIYcity apps.
These are not hard, fast rules for building things with DIYcity, but are rather guidelines for helping developers think about how DIYcity-type applications should be built.
These guidelines are now online at http://diycity.org/diycity-design-principles
Please check them out! Comments and suggestions welcome.