J. Oswald was a German company which started making novelty clocks in the mid-1920s. Their most popular models were clocks with rotating eyeballs, one eye displaying the hours and the other the minutes.
They had a number of designs, including dogs, genies, and apes, but their cross-eyed skulls are particularly awesome. You can occasionally find original Oswald clocks on eBay (the ones in good shape run around $1,000US), and there have also been a few knockoffs from other companies. However, there are several ways you could DIY something similar.
There’s a short Instructables guide for installing a watch face in a plastic prop skull; just install one in the other eye too. After setting the correct time on both, remove the minute hand from the one on the left and the hour hand from the one on the right. A bit crude, but it’d work.
A larger version could be made by stenciling a skull on a wall and using two round wall clocks for eyes. Remove the hour/minute hands as above, and cut a circular piece of thin black acrylic to fit over the remaining clock hands (see the eyeball clock sold by SUCK UK to see how to position them). That would give you the true rotating-googly-eyes effect but would still be fairly straightforward to do.
If you’re feeling a bit more ambitious, pick up a couple of small clock movements from your local craft store, insert them in the eye sockets of a plastic skull, and use small plastic hemispheres (perhaps a ping pong ball cut in half, depending on the skull size) to represent the eyes. Paint on pupils for the hour/minute markers. Be sure to fit the movements in so that you can change the batteries as necessary.
(via Shellhawk’s Nest)