1Seam Weld Steel Cylinders
I had a metal fabricator at All Power Labs in Oakland, CA, make a 5 element array for me. He charged me $220 for materials and labor. Once you have the resonator, you will need to make an RF amplifier to excite it. I made a class A amp. But if you are just experimenting with just CW, then a Class C amp is fine, and more efficient.