I made my own mostly using USB hardware. It starts with a USB hub with 4 flexible sockets, #1 USB to Serial adapter with breakout board attached for the RST/GND PTT function. #2 is a USB soundcard with case removed and wires attached to another circuit board with audio isolation transformers like the "Easy Digi" circuit. #3 has a breakout board for the USB voltage access. An Arduino style relay module with opto isolation is triggered by the RST signal, and powered by the USB voltage and operates as the switch for PTT.
With only one USB connection to the PC, I have three cables out to the radio for audio in, audio out, and PTT. It's all nicely squished into a small tin box with a notch cut in one side for all cables. I can post some pictures if needed. All components are wrapped in tape to prevent shorting each other out inside a metal box. Total cost of all parts used ~$5.00.
