So like a plug and play guitar amp?
Absolutely that!
I have finished building 2x 9 pin valve sockets (usually preamp valves) and a "Tone stack" which usually sits after the first couple of stages of preamp and before another couple then the power amp.
So with the power amp box, these two 9 pin bricks, the input stage I am building tonight and the tone stack brick we have a working guitar valve preamplifier.
I have the octal bricks ready but no sockets (which are on order) that will create the power amplifier section with an output transformer and speaker.
I will be launching all of the bricks plus others like a distortion brick, reverb brick and tremolo brick on thingiverse when they are complete. Either than or I'll become a millionaire and sell them fully built.
The tone stack box is the one with 3 pots, 3 banana sockets, a switch and 8 holes with .254" headers inside them. THIS setup is a standard FENDER tone stack. By changing the 3 caps and resistor then turning the box over and swapping out the pots for different values you can get a Marshall or Vox tone stack. You can also mess around and have something in between. The Tone stack box can be used stand alone to add a tone stack to an amp without one and then you can hard wire it once you have a sound you like.