Here is the visualized diagram for the project:

This means that I have to get bodyshells and underfloor parts for 1 R3 trailers, 3 R5, and 6 R6 trailers, as well as 10 articulated bogie parts, underfloor and bodyshell for converting R1 to R8, and motorized bogie and power unit to motorize M2.

I will do this in 2 stages, in which I would acquire 5-6 of the trailers first and test it, and get the rest.

After the testing is finished, I would either request for a repaint of these models in one of the model shops I know that does these, or repaint it myself.