I have had thoughts of sticking my dick in a cow milking machine also. It doesn't necessarily need to be a cow milking machine but feel really good.
I have a milking machine that I bought on eBay. I just modified one of the teat cups to fit my cock. With lots of lubrication and the right pulsation speed, that machine brings me to mind blowing orgasms. Some of the most intense orgasms of my life have been caused by the machine. It's a great way to masturbate.
I've never tried a milking device, but there are tons of farms where i live, so maybe i'll sneak over one night. No doubt your can buy a cheaper & less dangerous suction device at an adult store or order one online or from a catalogue. Besides, having a milking device in your bedroom might be hard to explain to the people you live with or guys you bring home. Speaking of guys, THEY are the best suction device of all! I've gotten blown by women, but guys are far better. Straight guys have no idea what they are missing!