i'm a big fan of all the map / compass / clock skills.
if you can find true north, you can then use that knowledge to make a sundial.
there are a lot of ways to make a sundial with varying degrees of accuracy. the trick is that you either need to plant it in one place and construct it to be accurate for its place and season, or you need to angle and orient it whenever you use it to have the hours line up properly.
i like this little number from sky & telescope because it has an easy to use printout page that you can use to build an easy and pretty accurate sundial. you have to face it to true north (or south, if you live in the souther hemisphere), but if you've folded it to match your correct latitude, it's pretty accurate. you have to adjust for daylight savings on your own, but it works.