I use a fine threaded 8mm bolt with a few jam nuts to lock it onto the bevel gear side of the crank and made a pointer out of aluminum and mount it to one of the clutch cover bolts, this works great for setting up port timing and a wheel can be printed on both sides of the disc so it could be read from either side of the engine while mounted out of the way on the clutch side...
I made my degree wheel by printing a picture of one off the net then gluing it to a plastic sheet with spray adhesive, you can print a degree wheel onto card stock as well but it'll last a lot longer if glued to a sheet of plastic or even an old cd.
Here's a pic of mine mounted on an engine to set up port timing, it can also be used for ignition timing and will stay put while running if the engine is started with a pull start. I just got the image by doing a Google image search for "degree wheel" and there are several printable ones to choose from...