Please forgive me if this is in the wrong section.

I'd like to start off by saying that I do not know much about doing this stuff, but if given instructions or schematics I can usually figure it out alright. I don't know where to start with this so I hope someone here can help me out!

I'm looking to build an instrument and I'll list off what I'm looking for:
drone instrument
two clean tones
both able to sweep the range with use of two twist knobs
individual volumes would be great, but a single volume would do the job
1/4" output
runs on batteries would probably be most easy for me
small enough to fit in a project box that will fit on a guitar strap
interested in a range on the lower side, like maybe an octave below an electric bass?

Any help that you can offer would be GREATLY appreciated, even with teaching me proper terminology.

Thanks!