Here’s something a little different. It’s a synthesizer Voltage Controlled Filter module (envelope filter) and a Sample & Hold module all in a stompox suitable for guitar (and other instruments). This is listed as Maestro Filter Sample/Hold, but it is exactly the same circuit as the Oberheim Voltage Controlled Filter. The envelope filter on this unit is excellent for guitar and bass. Of course the main attraction is the sample & hold, which is rare to find in a stompbox for guitar (or bass). A big Thanks to Rick Lawerence, R.G. Keen and Aron Nelson for helping make this project happen!

Description from General Guitar Gadgets.