This is my first fpv drone, I set myself the goal to be able to fly sub 250 with a small battery and to keep the drone working with larger lipo's.

Space contraints:
I will say that if you are thinking about building this, it's not straightforward;
the capacitor doesnt fit between the stack and the o3 so you need to rotate the stack 180 degrees.
The cap doesnt really fit there either so you have to put the cap on extention wires.

Weight constraints:
The weight budget is EXTREMELY limited for this quad, I had to take some pretty drastic measures to come in below 250g:

• I used 2 bolts per motor
• Almost all tpu parts were removed, only 2 pieces of tpu protection on the front arms are left.
• The front 2 standoffs behind the camera cage were removed.
• The o3 was flipped because I it allowed me to shorten the cables, it also allowed me to route the antennas along the arms (bad for range, I know) I fixed this shortly after, look at the upgrades at the bottom of this post

NOTE: the picture shows 250g but I was able to remove the SBUS wire from the o3 and shorten some other wires so it was 249g when I was done with it.

Flight performance:
Stepping into fpv with a pair of digital dji goggles was amazing and so was the quad, It's powerful enough thanks to the 16mm motors and it's fast! I chased a car going 90-100kph without issues. Flight time is also decent, 3 minutes ish when going full ham and I chased a car at ~30-50kph for ~7 minutes so that's pretty good in my opinion.

Upgrades
I did want to upgrade to an ep1 receiver to not have to worry about the ep2's limited range. I highly recommend this option as I had 2 cases of sketchy rx signal when flying 100+ meters away.
Also the o3 antenna's are now routed through the pigtail hole in the back of the top plate. This gives a more stable signal.

I weighed the drone again after some use and it's 251g now, not sure if that's dirt or if I modified parts and don't remember it. If I were to build it again I'd use the new fancy purple speedybee f405 aio. It saves like 6 grams and that gives you a good margin.
The receiver cover
https://www.printables.com/model/926267-volador-35-elrs-ep2-mount