I particulary like the shape and material of the box (what was its "1st life" ? where did you find it ? what are the dimensions ? was it originally drilled ? )
I wonder if you have put that 12VDC PSU in the stompbox or is it external (wall-wart style) ?
I did not tried yet a lo-voltage tube ovd, but only hi-voltage designs - thinking that it doesn't sound as well as hi-voltage tube ovd, relying on some friends trials heard - but I am probably wrong and will dig it personnally.
Does your release tends to sound bluesy-smooth-subtle "vintage amp-like" overdrive, with a nice regular decay and overdrive fading with the note, or is it more "heavy distortion" orientated ?