I'm embarking on a little project with my daughter. She is greatly into fantasy things, game books etc. While on holiday she picked up 2 wood burning carvings, one for her friend and one for herself just to be used as wall hangings but I mentioned that they could look good as clocks so that's the path we are taking. I have ordered 2 clock mechanisms and purchased some brass upholstery tacks to act as number positions on the clocks but I want to be able to print out a fairly accurate pattern that I can overlay onto the wood so I can drill accurately. I want to pre drill the holes where using an undersized drill so that when I tap the tacks in the wood wont split, I will also add a dab of glue. So what free to use software is available to do this, I have dabbled with sketch up but to be honest I didn't find it very intuitive to use.
To be honest - in terms of free stuff, all I could muster was sketchup. I've been giving this a bit of thought for you, and I've come to the conclusion that it might be easier to do it with a protractor and a piece of paper though, and a pair of compasses. Go old school. Mark out a circle from a centrepoint on a piece of paper the same size as you want the drill pattern to be on the face of the carving. Then it's as simple as making a mark (which for argument's sake can be the absolute top) and then working out the markings based on 360*/12 That's what I'd do in the workshop if I didn't have Solidworks.
A big thank you to 13eightyfour for laser cutting me out a driiling pattern on card board it made it so much simpler to do this little project.