Endorphin.es present the rather simple but ever so useful PLUS 3 - desktop expression and sustain pedal that adds controls and unlocks features in MIDI controllers, synthesizers, effects pedals and semimodular / eurorack instruments, some in ways previously not possible

PLUS 3 is designed for musicians who prefer compact desktop control of features accessible via the sustain and expression jacks of their instruments, as opposed to using their feet or bulky sustain and expression pedals on their desk.

PLUS 3 includes a high-quality fader for expressive performance and automation, a momentary sustain key, and an innovative "drone mode" toggle switch, which lets you free your hands and hold notes indefinitely. In drone mode, the momentary key's functionality changes, to let you swap droned notes with new ones.

PLUS 3 is totally passive, meaning it doesn't require any power to work. It's made of aluminium, so it's sturdy, light, and portable. Its sustain key is based on standard mechanical keyboard-style keys, so you can customize it and swap the key out to make the pedal your own with your key of choice.

Capabilities PLUS 3's sustain side unlocks for instruments with a sustain jack, subject to the instruments capabilities are among other:

A momentary sustain button for instruments that don't have a dedicated physical sustain control (most don't!)

A dedicated drone / hold / arp latch switch for instruments that don't have one (many don't!). It's important to note that even if an instrument has a hold button, its sustain jack may unlock additional functionality or behaviour (for example, a button that simply holds notes does not cause Piano VSTs to resonate sympathetic strings in the way using sustain does.

Momentary and toggle control of any parameter mappable in your DAW synth's mod matrix / menu system, or effect pedal (for example, sostenuto, a freeze effect, dry / wet bypass, swapping presets, etc)
Capabilities PLUS 3's expression side unlocks for instruments with an expression jack are, among other:

PLUS 3 is particularly useful for adding an expressive physical fader to MIDI controllers that don't already have faders, but have an expression jack (for example, Native Instruments Kontrol MK3, or M32; or Korg's KeyStage).

Use PLUS 3's fader for direct access and expressive control of any single parameter mappable in your DAW, effects pedal or synth in ways not possible with a regular keyboard (for example, bowing a violin, an orchestral swell, fine tuning a track's level in the mix)

For DAWs, synths with a mod matrix or effect pedals with expression jack mapping capabilities (e.g. many Chase Bliss, Boss, EHX pedals, and the GHOST and GOLDEN MASTER pedals), use PLUS 3's fader as a macro control to change multiple parameters at once - almost similar to preset morphing, based on your instruments ability to map its expression input to multiple parameters