This is a list of components and parts regularly employed in my modules, and where to get them.
This list is not exhaustive nor guaranteed to be up-to-date . If you find any error, or want to add an additional source, feel free to comment below.

Connectors

Vertical Jacks 3.5mm Mono

• “Thonkiconn” (QingPu WQP-PJ301M-12, WQP-WQP518MA, WQP-PJ398SM…):
  • Thonk,
  • Synthcube

Horizontal Jacks 3.5mm Mono

• Cliff S6/BB (FCR1281, CL1384 etc):
  • Farnell (FR),
  • Rapid,
  • Reichelt,
  • Smallbear Elec,
  • Synthcube
  • TME

Cliff Jacks come under a lot of references, which can be a bit confusing. The common reference is S6/BB. The variations are about the contact plating, the terminations (for PCB or wires), if the connector comes with a nut or not, and some obscure, very specific variations that you won’t probably encounter anyway.
CL1384 and FCR1281 seem to be the most common, and correspond to the footprint employed in my designs. They are for PCB, with the nut.
Please, have a look to the following datasheet:

• CL1362
• Cliff CR1283
• JACK-3.5-MONO-FCR1281

Vertical Jacks 3.5mm Stereo

• Stereo Thonkiconn (PJ366ST)
  • Thonk

Hardware

Knobs

• Colored cap “Nose knobs”: SynthCube, musikding.de, TME
• “Davies 1900h”: SynthCube, Thonk

Integrated Circuits

• OTA 13700: Reichelt, LCSC/JLC, Tayda

Potentiometers

• 9mm Right Angle (Horizontal) “Alpha”
• 9mm Vertical “Alpha” with bushing
• 9mm Vertical “Alpha” without bushing

Arduino

• Arduino Nano compatible
• 15-pin socket connectors for Arduino Nano