I built this transfer caboose for a friend's railway. Scratch built to 1/48 scale out of styrene with metal grab-irons etc. and a wooden deck. It covers a heavy brass cleaning component, trucks are Atlas (I think!).
Hello. I have not done much with die-cast cars (I assume you are talking cars) lately but I seem to recall that Testors and Bhurago did some simple kits. The bodies were die-cast and the detail parts mostly plastic. You don't need anything special to assemble them. If you start to disassemble built models to modify them then I would suggest a good fine-tooth saw (Zona) and an assortment of small and not so small files, sanding supplies and fillers for metal. Checking out the various builds posted on this site (not just die-cast) will help point you in the right direction.
Hopefully this link will work. The thread will give you some idea of the process.
The tender is mostly styrene with a bit of brass for strength.
You will get lots of opinions on the 'correct colours'. Try and find colour photos or video and use them as your 'best guess'. I harken back to a pic of a B-17 fresh off the assembly line with three shades of Olive Drab, depending on whether it was a dope or paint or laquer.