For this kind of project, SketchUp is a great choice. MUCH simpler to use and faster to learn than a "regular" CAD program. There's a free version available from Google that you can try out.

-Jimdoria (February 08, 2007, 11:06 AM)

One caveat with SketchUp:  I've found it difficult to do exact dimensioning.  It requires some mouse-and-keyboard-fu, and changing dimensions after the fact is difficult enough that I've found it easier to delete missized objects and start over.  I'd prefer a parametric CAD system for generating plans for fine furnishings; that is to say, anything I was putting inside as opposed to a garage.

Or, you can use pencil and paper, as I did for my headboard, which came out fine.  I'd suggest getting a good, ghosted grid paper; I'm partial to the engineer's computation pad myself.  It is green paper with the grid printed on the reverse so it just shows through.  Of course, I'm an engineering student, and always have this stuff around, so I may be biased.  A light, ghosted grid is essential, though, since it lets you use an erasable pencil without (1) damaging the grid lines, and (2) confusing your lines with the grid.

You could start a collaborative writing thread just for the heck of it, nudone, though as you say it isn't exactly in the spirit of NaNo, where the focus is on personal achievement of a seemingly impossible goal.  That, and sleep deprivation.  It might still attract a crowd, but of course there's only one way to find out for sure.