Mission acomplished! I managed to fit an octave pedal in a 1590A enclosure. It is not hard because you don’t have any potentiometers at all. That’s why I chose this effect to be my first 1590A project. It sounds great, by the way, thanks to the guys in tagboardeffects for the layout:

http://tagboardeffects.blogspot.com.es/2016/11/earthquaker-devices-tentacle.html

In order to save space, two rows have been omitted from the layout, so it is 19×9 instead of 19×11. There are two rows with no components, they can be saved by using small resistors and ceramic capacitors.

I have put the octave after wah and compressor and before overdrive, not sure if that is the right place, let’s give it a chance.