I too have countless hours reading antennae posts, using site calculators, finding cheap supplies, etc. seems like you need to be into the thrill of experimenting, have the tools, meters and etc to make it worthwhile. For beginners its probably worth it to buy one. Theres a thread here about a $20 super cantennae, no results but looks ok for the price, lightweight. Also Hyper link has some nice ones for $45-$65. Could save time trying to figure out if what you built is any good. I also wonder about running around pointing some homebrew antennae around, it is microwave after all. Wonder about the guy with it in his back pack, or in the back seat of his car. Don't think I would want to do that for long periods. I have also seen alot of contradictions in calculations for sizes, lengths, that have my head swimming trying to make sense. But I like building so I made a couple to try out. JMO
PS Welding rod comes in 5 lb cans that look like a pringles can but more durable 3.075 by 14 inches. Little small on diameter but then you don't have to eat those chips. Welding shops throw them away.