Very cool to see that there are other hams here as well. It's a quiet hobby, but a very interesting one to say the least. I have built a number of antennas from stuff laying around the house, and saved a lot of money. After recently purchasing a dual band HT, I converted my 2m j-pole over to a dual band "Copper Cactus" antenna.
I was bored one day so I then built another dual band antenna and have it hanging in the garage attic. This is the "Arrow" design, and is a talking machine!
I've also built 2 ground plane antennas for 2m and 70 cm.
I also made a tri-band inverted "V" dipole in my attic that is just #12 THHN wire and a balun. It covers 10, 15 & 20 meters, even though I can't use the 15 & 20 meter frequencies yet.
It's like our fly-fishing hobby where it feels real good when you put something together and it actually works.