Hi Malcolm,
Yes, Scorpius (John) mentioned it earlier in this thread (with links to relevant webpages.. people were doing it for years,
http://techref.massmind.org/techref/pcb/etch/c84-st.htm)
However, if not mechanically modified, printers on DVD/CD will also have size limitations..
Still, it is worth trying, for smaller boards. The outcome will also depend on ink used, some inks are better than others (those issues are also discussed on the above mentioned web pages..)
EDIT:
Direct printing with un-modified CD/DVD printer (bottom of the page)
http://techref.massmind.org/techref/...kjetresist.htm
http://www.youtube.com/watch?v=p9W6mWtA8YM