Build Your Own Clone has been working on this pedal for a very long time. After about a year of R&D, they finally released this pedal. It's basically a custom flanger that contains aspects of nearly every flanger you can think of. The real cool thing about it is that you can customize it to whatever flanger specs you'd like with just a few component swaps. There's an optional V3208 Bucket Brigade Delay chip that you can buy, and I recommend adding that to your build. It's cheap enough to where it's worth at least checking out.
As always, BYOC did an excellent job at laying out the instruction manual for this pedal. Every piece has an order, and it's clearly written out and easy to follow. Today's switches are even PCB mounted, so it makes dealing with pots and switches way easier. You don't have to worry about running as many wires as you used to with the older builds. However, this pedal is a bit bigger. You'll need a bit more room on your pedal board to house this mammoth of a flanger.
The sound of this pedal is pretty much unlike any other. They combined so many different features that it's hard to describe exactly what it's like. On top of that, you can build it to different specs to totally customize it to your liking. You can make it sound similar to an A/DA, an MXR a BF-2, etc. However, they won't sound exactly the same as there are some unique things that only BYOC has going on. The overall flanging depth is fairly good, and it can do those jet plane sounds convincingly. You can also use it to simulate a quasi-chorus sound and thicken up clean passages.
Those looking for a versatile flanger that won't break the bank should definitely try this out. Be careful, though. A lot of people seem to mess up this kit because they rush it. There are a lot of components, so be sure to read the manual multiple times and take your time. It only takes one small cold solder joint to make the circuit inoperable. Thankfully, there's a helpful forum that can assist you in fixing it if such a problem were to arise.