At last, I have a photo that looks pretty close. I have now finished Grandpa's hands and the section of the traction engine in this area. I am pleased with how the lights and darks as well as the brighter colours in this area help to draw our attention from his face to his hands and the engine.
When I paint I'm not only thinking of the objects but the emotion or 'story' it helps to convey as well. I wanted to make his hands tell a story. To a model engineer his hands are so important. They are used to craft, with such care, the tiniest details but they also have to be strong. They are also older hands full of experience but at the same time worn with age. I have included a close up of this section in the next photo.