Here is the beginning of phase two by having three filter cells and a oscillator card for each. Enough room for a audio amp if needed.

If this project shows enough merit then I will switch to pcb to be truly hand held but in the development stages cardboard still reigns :-)

This is the basic 555 circuit used times 3. Transistors or other circuits can be used in place of what I came up with.

Sorry for the lousy image...