You can buy appliance touch up paint. It is in a small spray can. Its quite durable.
or You can try white nail varnish. Both dry faster than the usual paints.
Peter
All you need is the ability to format a google query.
In this case I used "melamine cutting"
Also I'm about to build some more cages so the info is personally useful
You could also try a product called Flowcoat, it is available from most marine shops. It is the same stuff boats are made from, it is chemically cured, heavy bodied so it will not be absorbed as readly into the chipboard and is fairly inert. The whole raw edge can be sealed and dressed to look pretty.
fuscus not all peaple realize you can find anything you want on the net and if they did, the questions we get asked would not need answering ,(shhhhhh i like reading your comments,you have taught me a lot already)