I found this clock in my local charity shop a few weeks ago. It was pretty grisly to look at, not in the greatest condition (faded face, peeling varnish) and cheap as you like. In other words, the perfect restyle candidate.
The only thing I was really concerned about was how easy it would be to take apart. Thankfully, it turned out to be a breeze - the face lifted away so easily that I actually ended up having to apply a little glue at the edges to hold it back in place once the project was finished.
With the glass carefully set aside, I unscrewed the clock mechanism (if you're doing something similar, be sure to lay out the pieces in the order you need to replace them later on. Take it from someone who hasn't always done this in the past...) and then peeled off the decorative cardboard face.
I then rough-sanded the peeling varnish, before going back over the whole of the wooden clock surround with a finer grade of sandpaper, ready to spray on 3-4 coats of gloss-finish paint.
Once that was dry, I traced around the original cardboard clock face onto some patterned paper, cut it out and adhered to the centre of the clock. You could obviously add numbers at this point, but a busy print like this looked better without.
The hands and clock movement screwed back into place really easily, and with just a small amount of glue to hold the edges of the glass in place . . . one restyled clock, ready to hang and remind me just how late I very probably am.
One quick tip: if, like me, spray paint is something you struggle to get hold of, particularly in a good range of colours, it's worth trying either the London Graphic Centre or (a little less obviously) your local branch of Halfords. I wouldn't necessarily recommend using their car paints on paper projects, but for more solid pieces, like the clock here, they give a really good, tough finish and are relatively inexpensive - around £6 for quite a big can.
And if it's a clock like my thrift-store find you're after, there's currently one here on eBay. Let's just assume the bit where it says 'very rare' is a case of fancy seller-exaggeration, rather than an indication I've just wrecked a priceless heirloom with a can of green spray paint, ok?