I considered building the head myself. I had built one years ago. However
the GWS dragonfly parts are so inexpensive it seemed silly. The entire head,
swashplate, linkages, head bearings, etc. came to less than $40. I assembled
it in about 15 minutes. I took longer to make the shaft mount and anti-rotation
loop than it did to build the head. I included a closeup photo if you want to
reproduce it yourself. There are however simpler head designs that accomplish
the same thing and can be found in the various model helicopter design books.

As to the CG. When I hold the gyro by the rotor(flybar actually) it hangs
such that the rotor mast is vertical, i.e. nose down. I have flown it
with various CG configurations by moving the battery and it doesn't seem
to matter a whole lot where the CG is within a range. It gets a little "pitchy"
with aft CG but not impossible to fly.

The flying weight is about 12.1 ounces (342 g). Total rotor span is 26-1/4".

The power plant is a GWS EPS350, "D" ratio, with an APC 10x4.7 slow flyer prop.
The Motor is slightly retimed as has been widely published but if need be I can send
a photo of exactly how much retiming I did. It is a simple matter to twist the end bell
with snap ring pliers.

Speed control is the Castle Creations pixie 20 P.

Battery - Apogee 1050 3S1P ( 3 cell ).

I think the motor draws in the 7-8 amp range in this configuration so
I believe this about 75 watts, likely 40 delivered to the propellor.
I considered putting one of my brushless setups in so I could use a smaller
battery but decided to hold off until I build a new gyro that I spend more than
two hours building. The chassis is pine stock cut on the table saw with no
attempt at lightening, the next one will be lighter.

Thanks for your interest.