$6 all weekend rental, right here--OH YEAH!!!
I used a friends once that made one from a giant C-clamp but it ended up grooving my valve ends as I tightened or loosened it, he hadn't added a dual spinning head type thing so, every time I twisted the throttle of it..well...ya get it...
So I'll get one one day--
This is a good topic
Tools...good tools always good