Scratching head ??????.
Thank you pcas1986. That comment explains to me perfectly why I can't complete a "simple loco" in Gmax or get further than a cube in Blender. I guess I will have to resign to the old adage "you can't teach an old Doug new tricks"

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Doug.
Sorry, it wasn't my intention to confuse. Perhaps this might help:
These shots show a cube in Blender. The first shows a simple cube with several materials of different colours "assigned" to different faces. These are colours created by Blender. The UV editor, shown on the left, has a blank image of size 1024*1024 with the cube mapped to that image.
In the second image I have baked those colours using the textures option to the blank image using the UV map. I then saved that image as a targa file (raw) with a filename of bake.tga.
I then saved my Blender image as 1.blend and then saved it again as 2.blend. I deleted all the materials (red, blue, etc) and created a new material called test.m.onetex and created a diffuse texture of type image and loaded bake.tga into that texture. Because the UV image still exists in Blender it will map exactly to the colours in the bake.tga file.
This is the new material and texture in Blender:
Here is the cube as a scenery asset TANE's Preview Image utility:
In my example I have just used simple colours provided by Blender. But you can paint on to the mesh using texture paint with a simple brush or even a stencil using an image. These techniques I am still exploring. I did create a tutorial on this process and gave it to a couple of people to try out. It needs work!
Painting onto a cube is relatively simple. But painting on more complex meshes becomes more difficult with the detail of the mesh. A house, such as Mick's example, is not especially difficult but locos...
(Edit: A point of clarification: when using a brush to paint on a mesh, the "paint" is applied to the texture in the UV editor as well so painted parts do not need baking. You can still bake shadows, ambient occlusion onto that paint.)
Then there are the issues of adding staining, weathering, etc.
I'm still learning this stuff. The more I learn, the more I realise I don't know.
p.s. I'm an old dog as well.
Cheers