Another showing DIY tri-rotor helicopter W.Thielicke He done a great job! the building log available as PDF and the little a bit tricopter specs below.

Controller: Atmega32 @ 16 MHz
Gyroscopes (pitch, roll): ADXRS610
Gyroscopes (Yaw): Murata ENC-03R
Accelerometer ADXL322
Receiver: ACT DSL-4ST
ESC: Tower Pro n18A with I2C Modify
Motors: Scorpoin S2212-26
Propellers: EPP 10×45″
Battery: Kokam 3s, 3200 mAh
Frame: CFK coated plywood + CFk tube + Delrin (POM) hubs & spacers
Serial Data Link : Xbee Series 2
Endurance: 14 minutes
Source : diydrone