Build a tube Mic Pre: Build Your Own Two Channel Vacuum Tube Mic Preamp! | Tape Op Magazine | Longform candid interviews with music producers and audio engineers covering mixing, mastering, recording
Poor Man's Tube Compressor | GroupDIY Audio Forum
Tube Opto Compressor Chassis Kit
Vacuum Pump 12V Mini Diaphragm Air Compressor with Silicone Tube : Amazon.co.uk: DIY & Tools
Sound Skulptor's MU524 Vari-Mu Tube Compressor is now available