i am using 1/2 inch metal conduit and it is working well i use a bender on one end of each joint and then slip an inexpensive connecting collar and use selftapping metal screw to hold them in place. as for using wire on trellis i buy #12.5 hitensile wire at .02 cents a foot from kencove and even at 1000 ft plus shipping its not that much

I partially agree with "johngreenhand". It's an informative and I hope it should be effective.