A while back LMNC released a video on a soldering marathon for the Erica Synths Elektor Formant synth: https://youtu.be/nmlrqQjZxv0?feature=shared
Earlier this month, Erica Synths started offering their kits for their Elektor Formant kit on their website, where you can find assembly files for download that are very useful for SDIY!!! https://www.ericasynths.lv/shop/diy-kits-1/elektor-formant-system/?v=3504
The files include a scan of the original Elektor Formant booklet, and per module in a subfolder mostly starting with ‘Main..’ in the name a PDF file of the schematic. These are very useful for synth DIY, as their entire system is build for +/- 12V, instead of the +/- 15V of the original Elektor Formant system.