I would love to be knowledgeable and skilled enough to be able to design sound synthesizers and audio gear from scratch. Well, I am not yet clever that much, but this does not diminish my enthusiasm for DIY electronics and sound creations!
Luckily there is an abundance of very creative and skilled people out there, whom are designing DIY kits for people like me. Much enthusiasm with limited proficiency in electronics and music.
These two Lo-Fi noise boxes – the Alien Screamer and the Weird Sound Generator), are the design of a much celebrated synth guru Ray Wilson. Sadly, Ray passed away a few years ago, but his legacy lives on. His family runs the website which was set up by him, with the visual ascetics of yesteryears, which I like a lot. If you are after very good info on DIY audio projects and have not seen this site, you should do it straight away by clicking here: Ray Wilson- Music from Outer Space. Furthermore, he has a book as well on building synthesizers, which was published by MAKE! (this is an Amazon link), if you are interested in this subject, that would be money well spent.
Both the “AS” and the “WSG” are excellent starter projects (the Alien Screamer is simpler). You can choose to build one from absolute scratch, following the schematic and build the circuitry on a blank vero/ stripboard or if you want to save some work or you are not confident enough, you can buy a ready-made PCB, full BOM (bill of materials) and even a faceplate for your project. I have opted to buy the PCB only and being based in Scotland, there is a UK seller whom has the right to commercially produce a lot of the MFOS projects.
The MFOS website is a great source of information, you can find schematics, BOM, template for the faceplate, even modding options, so basically everything you possibly need to build both of the projects. Hence, I am not going to paste these docs here, but have made a few pics as I was progressing through the built, so here is the story in pictures (and some text).
Alien Screamer
Variable resistors wiring 
PCB is fully populated being mated to the faceplate 
Face plate wiring with 1/4 switching sockets for mods 
This design has its own amplifier, so you can have a built-in speaker 
Handwritten faceplate design… 
Wholes are drilled for CV IN and Audio Out mods 
Small resistors and capacitors are installed
Weird Sound Generator
Designing Faceplate layout 
Not a straight line in sight… 
Peel off satisfaction guaranteed 
OCD 
Faceplate wiring 
Wiring attached to PCB 
PCB all done up 
CV out mod, it somewhat works by making more crazy noises 
The finished machine 
Post-Apocalyptic Synth
Test Sequence
Testing time 
CV in mod testing
Creative 