The PW3B-LPF onboard bass preamp uses fairly standard Bass and Mid controls coupled with a variable resonance, swept frequency Treble control format, with a separate control for each function. The latter part is often called a "filter" EQ in the bass world, which is a bit confusing to many techs and engineers since pretty much all EQ circuits are actually filter based. VRSFLPF is a bit of a mouthful though, so call it what you will.
Nominal current consumption with the preferred opamp pair is less than 1mA and all potentiometer values are meant to be reasonably easy to source. Board size is 2.21" by 1.66" (56x42mm) and the circuit can be powered by 9-18 volts, with all field testing so far having been done at 9V.
The printed circuit boards will be available from a very reputable U.S.vendor directly from the shared project section on their website. They sell in multiples of three, so many of us will likely end up with a test build, a "real' one, and one for a friend. Bills of Materials using two of the most popular U.S. vendors will also be done as shares on those vendors' websites, and also posted in the Wiki to allow builders to source parts elsewhere as needed.
The current schematic is always accessible from this link: passinwind.com/PW3B_LPF_OpenSourceLicense.html.