Inspired by one of leftaroundabout's answers, I got a Monotron and I love the wicked tones it can make.
I have the dual-oscillator version so I tune by pressing the 'G' (or whatever note) and adjust the left oscillator to be roughly the base pitch that I want; then adjust the right oscillator to be in harmony with the first (the cross-mod knob makes it easy to fine-tune this relationship). Then adjust the 'peak' for gain, and use the filter like a wah-wah. I've been able to simulate most of my favorite incidental sound-effects from Doctor Who, like descending space ships and throbbing computers.
But, the ribbon only goes 1 octave (+ minor third, if you do everything in B-flat, but that high D-flat is hard to hit with my manly fingers).
Is there any way to get more 'length' out of the ribbon? I can adjust the primary pitch, and the second oscillator stays relative so the tone doesn't go wonky, but it's very difficult to tweak the knob exactly 1 octave.
Are there any simple mods to extend the coverage of the ribbon, or install a larger ribbon, or maybe glue a long lever on the pitch knob for more precise tweakage? One octave of melody-making feels really limiting.