Six years ago I needed crosshairs and just used the first spider that I found (not a Black Widow). The trick is to get her to spin on command, it took half an hour for us to cooperate. She won her freedom, and I have a fine set of crosshairs that are still as good as new. Just remember protect them from prying fingers.
Videotape your efforts and you should win the prize on 'America's Funniest Home Videos'.