Well , I had also thought I'd like to do one of these for a while so I googled and found a few different ones and decided on this one from wooden-gear-clocks.com . They are not cheap but the quality is outstanding. All the parts are laser cut on 5 ply baltic plywood sheets. the instruction book is very clear and well illustrated. I didn't keep track of the time as i didn't work on it un interupted. Most of the work involves sanding and if you decide on paints, then the time to do the details. In any case the basics don't take long at all.
I've got it now where it is off about a minute in 3 hours. For watches that would be shocking, but if any of you have experiance with pendulum clocks you know that that is just a matter of keeping adjusting the bob. It is actually a very quiet running clock unlike it's brass geared brethren.