Here the body is being assembled:

The rule is being used as a square. I joined 1 end to 1 side and repeated this with the other two pieces. The two 'L' shaped halves are left to dry for a while before joining together.
PVA adhesive is used throughout, usually being applied neat in thin layers to both parts.
The recesses for the 'glazing' can be seen.
The 3 layers that make up the sides can be seen at the butt joint. I usually
chamfer the 2 pieces to be joined so the layered construction is hidden.
Now for the chassis section. I'm trying to use materials that can be found freely when possible. Attaching card to the Hornby chassis could potentially cause problems. This is the method I'm trying:
The original clips are being used, although the i-tunes card is thinner than the Hornby body or footplate.
The i-tunes card is sandwiched between layers of card:
This assembly will fit tightly inside the base of the body.
Here is the floor with side plates and headstocks attatched. Spot the mistake:


The clearance between the bottom of edges and the rail is about 0.5 mm. I've realised that I forgot to take any photos of the construction of this sub assembly so I will repeat it with more clearance.
(Ignore the date on the photos, the camera is not set correctly.)