Aaron Lanterman makes PCBs from some of the functions from the Buchla Music Easel. I made a 5U version of the Pulser and the Crossfader & Timbre Generator. Another of his PCBs is a dual Envelope Generator. Synthcube makes a 4U panel for it. Someone sent me a photo of their Buchla Dual 208 Envelope Generator module. Aaron's information on the PCB is on his Lantertronics Envelope Generator page.