craftgrrl | Felting: sink vs. laundromat

I need some advice. Everything I've seen on felting a knitted wool item (I'm making a bag - my first felting attempt) says to put it in a pillowcase and into the washing machine, then has some specific instructions on how long, how hot, what cycles to avoid, etc. I don't have a washing machine of my own, so I'd have to use the laundromat, and I'd have really limited control over temperature and cycles and things. Has anyone used a coin-operated washer to felt? How did it go?

I was thinking about just putting it in a sink full of warm/hot water and swooshing it around by hand - would that work?

So sink by hand vs. coin-operated washer. Please help. I'm excited about this bag and don't want to mess it up too badly.

Just so this isn't a completely needy post, here are some faux-mink

I made for a friend.