I was looking to build a new microquad right around the time the GEPRC Smart 35 was released. I really liked that setup and was willing to buy it as a BNF, but I wanted to use an existing naked Vista unit I already had, as well as the Runcam MIPI camera (I didn't want another Nebula Nano). So I decided to buy the Analog PNP version of the SMART 35, remove the analog camera & VTX (to use in my son's upcoming wing build), and replace it with my naked Vista and MIPI camera.

I wasn't originally planning to put this onto Rotorbuilds since this is largely a pre-built quad. However, I ended up making some mods, so posting this in case someone finds it helpful.

Runcam MIPI
With the stock camera mounting plates, the MIPI is too recessed into the frame due to the camera's short length and location of screw holes, leading to some of the frame/standoffs being visible in the FPV feed. To address this, I designed custom plates that allow the camera to be moved forward a few more millimeters (Thingiverse link). I was expecing to have them cut out of carbon fiber, but when I tested the design using 3D printed PLA plates, it worked without issue. So I'm planning to just stick with these printed ones. They've survived several hard crashes without issue, and there's no jello whatsoever.

I quite like the Runcam MIPI in terms of image quality. The colors look good to me, and it is much better than the Nebula Nano. I also like the idea in general of someone other than Caddx or DJI making DJI-compatible gear. At this point it looks like DJI will keep that interface open, so hopefully we'll see more third-party camera options.

Naked Vista
Nothing too special about this aspect. Similar to my Hornet HD build, I designed a holder for the lower PCB in order to better secure the UFL connector on the video antenna (Thingiverse link). In addition to this bracket, I just used some squishy spacers between the boards and the board and frame top place.

ExpressLRS
I'm in the process of migrating most of my quads to 2.4GHz ELRS. It's fast, cheap, and the integrated antenna on the EP2 receiver minimizes footprint. While it works great on my other quads, I initially hit a snag on this one: There is a compatibility issue with the GEPRC AIO board on the Smart 35 and the EP series receivers.

I temporarily ended up installing one of my trusty Crossfire Nano receivers instead, paired with a Minimortal T (as shown in the pictures on this post). Not as elegant as the ELRS EP2, but it worked. I designed a holder for the Minimortal ((Thingiverse link).

However, after I broke the Minimortal-T on my Crossfire setup, I decided to revisit ExpressLRS and successfully got my EP2 working by installing a pullup resistor on the EP2's RX line. I've outlined the problem and the solution in this blog post -- check it out if you are having issues getting ELRS to work with this GEPRC AIO board, or another AIO board.

Impressions
The factory tune on the Smart 35 is really good, which is consistent with the reviews I've seen. Only changed the rates -- didn't touch filters or PIDs. It flies really well, and I haven't broken anything yet after a few crashes on concrete. It's super quiet, and has plenty of power. It's not going to replace my 5" as my main quad for practicing/learning freestyle, but it's my go-to small quad now for those situations where 5" is not practical.