Got one of my favorite little blue boxes in the mail!
Blue ones are 3340 breakout boards by @Sonosus. They will make it easier for me to experiment with those AS3340 all-in-one oscillator chips I bought and will serve as the heart of an analog VCO module.
Red ones are busboards - based on Tomarus’s design and the 10-pin edit of it by @analogoutput.
I modified it to fit 6 headers in 10cm (gives you a better deal from JLCPCB), I don’t know yet if it works, but the circuit is really too simple to screw up.