A lot of posters on this thread seem to have the dilemma of wanting to use a CAD program but battling with its complexity and steep learining curve. I had the same problem and after trying a (freeware) CAD program or two I also just gave up in frustration.
Then I discovered a neat trick. Microsoft Word and Excel have a drawing toolbar. With this toolbar you can turn Word or Excel into a CAD program that admittedly is very limited but has proved sufficient for my requirements. I have done some incredible drawings in Word.
The drawing toolbar allows you to draw circles, arcs, lines, rectangles, triangles, random shapes, etc. and set them to an exact scale length. 3d, wire-frame and rotation of objects are also possible. Colors, shading and textures can be added. Simple objects can be grouped into more complex objects. These can be cut and pasted so you design once then just clone it everywhere.
Like everything, there is a learning curve and you will have to do a lot of experimenting and trial-and-error, but it is so easy that it is actually fun. The best way to learn is to load the drawing toolbar and then try every single item on it and go through all the settings and options. Soon you will be producing great looking drawings that are accurately dimensioned and scaled. I have my entire railroad designed in Word - track plan, benchwork, scenery, wiring, etc. and it is accurate enough to physically build from.