This is the micro build I love most. It's 90mm and flying pretty good. It's really small that allow me to fly it at many parks near my house, my 130mm build has been collecting dust for a long time.
Notice:

• The original frame is iflight-racer-ix2, but it arrived without the top plate so I try to fit the top plate get from another brushed kit
• The flytowner arrive with ESC DOA, I replaced with the Racerstar 4 in 1 6A 16x16 and it's working great so far
• I replaced all aluminum spacers by nylon M3 spacer, but trim it down to M2 size, the M3 screw much stronger than the M2 screw and the quad survive many crashes so far
• The battery is split from the 4s Tattu 450 mAh and it's rock on the micro build
• I really suggest to use the Matek super loud beeper. It save me a lot of time finding quad. I can hear the sound clearly from 30 meters

Parts list:

• Frame Custom
• Flight Controller HGLRC XJB : https://goo.gl/u9TMeL
• Motor Racerstar 1103 10000kv https://goo.gl/FSdX1X
• Propellers https://goo.gl/yKmUKf
• FPV Camera https://goo.gl/i5nSZ3
• FPV Transmitter https://goo.gl/DVt23k
• Receiver https://goo.gl/VSMJqx
• Super loud Buzzer https://goo.gl/Vf3p63

Fly video

Update: final PID tuning. I really love this build even ran into some big issues during building process : frame arrived missing top plate, ESC DOA