After many abortive attempts and much frustration because of my lack of focus, I finally crocheted one of these I wouldn't be embarrassed to contribute to the Breast Cancer Center of my local hospital.
I got the pattern from KnittedKnockers.org, which has patterns for Knitted Knockers, as well. I am not a great hand knitter. Crochet is much easier for me, tension-wise, but following instructions is not my forte!
If you know someone who has lost a breast (or two) they can get free Knitted Knockers from KnittedKnockers.org. If you know someone who would be willing to contribute Knockers to that organization they would love to have them.