I got interested and started building MP+ transeiver project of W8DIZ, Diz in 2003. I received serial number #2 from Diz, soon after having my first QSO. Here are the pictures that I took over several months while building the transceiver. You can find more details from the page of MP+ maintained by Diz.
Here is the final (?) version of Multi-Pig Plus #2:
Just to give an idea about the design, here is a collection of schematics of various modules of the transceiver (You will find a lot more details at the page of DIZ).