After months of delays, finally finished my DIY PF. It uses Fengru EMX500 drivers but can fit inside any 15.4mm MX type driver. Had many problems given that this is my very first diy project when it comes to audio. Inside, the brass had parts that needed to be sanded down in order to accommodate the front MX plastic shell, which also had to be sanded and thinned out on the sides plus shortened so that the brass back can fit (and the brass back had to be sanded in some ways as it wouldn't fully close without it). Tuning was also very difficult as this driver isn't exactly properly tuned for this kind of shell, so I removed the drivers at least 50 times before deciding that I had to use just a regular shell and no tape/foam/cotton on vents nor any inside walls. Cable, although beautiful imho, transfers a lot of noise while walking and is stiff. (Didn't have any heat shrinks, but would've used some, not that it actually needs any at this point). Currently, these things provide details for days and the sound stage is just massive beyond imagination, but there are some resonant peaks going on across the frequency response, and somehow, only happens when pushed loudly. These peaks are not unbearable and never come close to being sibilant, although there is some low-mid range bloat especially with piano (ironic...). With a different driver and perhaps someone to properly do the tuning for that given driver, these could easily be the most valuable pair of headphones that I've seen. Obviously, these shells resemble Final's way too much and there is a question of ethics (although, this is diy and not a real product..). Personally, I am still looking forward to buying the real deal, this was just something to bring me into DIY world and keep me entertained, but it resulted into a very good and beautiful thing.