Well I think I've gone as far as I can with the construction of the body. As the card roof represents roofing felt, I've glued a couple of battens on each side to make it look more like a shed.
Hinges on the door and the tops of the sloping hatches are made from the foil tray that dog food comes in. This is how:
A piece was cut, 6mm x 5mm. Using the bluntish end of a small chisel I pressed a groove in the centre of the reverse side. Turning it over, I pressed another groove, either side of the central one, thus forming a raised section. To form the screws I pressed four dimples with a rounded spike on the reverse side then gently flattened them on the front. This was repeated six times. The hinges on the lids were bent slightly then glued in place and the those on the door fixed flat. Finally a spherical map pin was used for the doorknob.
At the moment the body is a push fit on the chassis and may remain that way, perhaps with a little help from blu tac or double sided tape. I'm still undecided about buffers and couplings. All suggestions considered.
Also, I'm wondering how to get a weathered paint finish. There is, I think, an existing kit for what is called an 'Outhouse' loco, which has a lovely weather worn patina which I would like to achieve. What I may do is paint it with a mixture of thinned brown and silver and when the paint is dry, dry-brush with another colour. Again, any thoughts?