$6.95 - Raspberry Pi 40 Pin Wedge T Breakout Board - Tinkersphere
40 Pin GPIO Extension Cable for any 2x20 Pin Raspberry Pi [150mm / 6 long] : ID 4823 : $2.95 : Adafruit Industries, Unique & fun DIY electronics and kits
Raspberry Pi 40 Pin Extension Board Adapter Optional GPIO Cable Line Wire for Raspberry Pi 4B 3B+ for Orange Pi PC - AliExpress
Amazon.com: GeeekPi Micro Connectors Raspberry Pi 40-pin GPIO 1 to 2 Expansion Board 2 x 20-pin Strip Dual Male Header Double Row Straight GPIO Connector Pin Header Compatible with Raspberry Pi : Electronics