Amazon.com: Circuit Scribe Non-Toxic Conductive Silver Ink Pen – Award Winning Design That Makes Creating Circuits and Switches Easy As Doodling – Writes on Any Paper! : Office Products
CircuitWorks® MicroTip Conductive Silver Pen 8.5 g Line Width 1 mm | 04991-AB | SPI Supplies
Conductive Silver Ink Pen - Micro Tip [CW2200MTP] : ID 515 : $59.95 : Adafruit Industries, Unique & fun DIY electronics and kits