So here goes!
First I start with an idea. Usually a bonkers one which gradually gets tamed. I like to think "What does my railway NEED to operate properly" and then go about designing it in boring lessons with pencil and paper in oblique and side elevations. The overall dimensions are then checked in place on the railway and I can then get about CADing. I use 2D design for all my design work and what one has to do is mentally picture your final structure (engine shed) then take it apart in you mind and draw it. Here is the engine shed in the late design stages.

A little look at the finer work, windows and valensing.

Red for engrave, black for cut. The fine bits will be made of 1mm ply and the shell parts will be made of 6mm exterior grade ply.
We will follow this particular project to the final stages and end up with a building similar in style to this one...













