This one maybe?
It’s a bit more complicated, higher part count than my first. When I started using KiCad I went through a video tutorial and followed along to create a really simple LED flasher PCB (and got it fabricated). I had an original module idea or two in mind but decided for my first “real” project it’d make more sense to do something based on a known good, and not too complex, circuit. So I went on to draw up a PCB for a Music From Outer Space VCF. Two chips, three transistors, a couple dozen passives. Aside from getting some of the pot connectors backwards it worked (not that I wouldn’t do some other things differently now). Getting everything right the first time is not to be expected!
The octave divider might make a better second or third project — but I don’t think you’d be hopelessly over your head if you were determined to make it your first. Do take some time to learn about KiCad or whatever software you choose, though. Run through a tutorial and at least draw up some simpler designs first. And ask questions here.
(As for the octave divider — for a synth signal, where you’re dealing with simpler waveforms than with a guitar, there are much more simple circuits for octave division. This one for example.. But maybe the Mutron clone has some features that one doesn’t?)