Available as an assembled Module and as a DIY project.
This Module is currently available.
ADSR Envelope
The SetonixSynth DOUG is a simple-yet-powerful single ADSR module, made to deliver a wide variety of useful envelope styles in a small package. A true WYSIWYG design, the user can patch Gates, Triggers, or Square-Wave LFO’s into Doug’s Gate and Trigger inputs and quickly dial in the perfect envelope for percussion, rave stabs, ambient swells, you name it! Perfect for obsessive twiddlers.
These merchants probably sell this module. Huh?