Here's what the tool looks like:
And for $10, I wouldn't advocate bothering trying to make your own. I inherited a home-made job with my first FC, and it was useless. The proper ones are made of decent steel that's thin, but doesn't flare at the ends.
Once you get the tines in between the washer and the handle, give it a slight twist and you'll be able to see the circlip. More than once I've discovered one that had been fitted back-to-front this way.
Another tip: cover the right-angled end with electrical tape: it's awfully easy to scratch paint with...
cheers
RET
[edit: better pic]