Making own vehicles in simutrans is very easy. The most difficult part is the drawing: Go ahead, draw something. Or, if you want some for pak64, then you can probably reuse some from TT-paksets with very little effort. If you can solve copyright issues, there are like 10-15 trains in the 2cc set, which can be easy converted to Simutrans.
I like to look at great maps and see how things flow. A little like a finished model railway, but it is evolving and actually never finished. http://www.simutrans.com