FAA ARC Recommendations Final Report

[electrotor]

In summary :

The ARC's consensus report recommends establishing four small UAS categories, defined primarily by risk of injury to people below the flight path. For each category, the group recommends assigning a potential risk linked to either weight or impact energy. The report also addresses operational restrictions and standards to minimize the risks associated with each category.
The FAA will use the information in the report to develop a flexible, performance-based proposed rule. The public will have an opportunity to comment on the proposal based on the ARC's recommendations.

http://www.faa.gov/uas/publications/media/Micro-UAS-ARC-FINAL-Report.pdf

[electrotor]

I have just had time to do a quick scan. The four categories seem to cover only manufactured  models; I can't seem to find anything about home-made.
In any event this is not destined for the UK.