It’s part of their DIY series of educational and affordable Eurorack modules
The latest in their mki x es.EDU project of educational DIY kits in cooperation with Moritz Klein is a versatile envelope generator. This series will will consist of nine kits plus the enclosure and power supply unit to compete a fully featured modular monosynth. It will include a sequencer, VCO, wavefolder, noise/S&H module, mixer, VCF, envelope generator, dual VCA, and output stereo mixer with headphone amp.
They describe the EG: “Many iconic sounds like the squelchy acid bass line, snappy techno kick drum, and swelling dream pop pad wouldn’t be possible if it weren’t for envelope generators. So the EDU DIY EG is slightly optimized ADSR envelope generator, since it has only three controls. With sustain on it outputs an ASR (attack/sustain/release) envelope, but when the sustain is set to a minimum it becomes an AD (attack/decay) envelope generator that ignores gate length. Release and decay are controlled by the same knob, while a looping function and an inverted output make the module highly versatile for complex patches.”
You’ll need two EGs if you’re building the entire system, but they’re only $69/€55 EUR (VAT excl.) each.