I recently built a Full Wave Delta Loop based on this document from GU3WHN (I don’t remember where I found the document)
I used an LDG 4:1 Balun: I purchased mine from Amazon
For wire I used BNTECHGO 18 Gauge Silicone Wire also purchased from Amazon. I’ve seen a few youtubers speak highly of this wire and it does not disappoint!
I have mine mounted horizontally. The feed point is on a 10′ pole on my deck. The wire goes from the 4:1 Balun to a 3D printed insulator in one tree to another insulator in another tree, then back to the Balun. The antenna is roughly 25′ above ground.
Once the wire was in the air, I used a NanoVNA and tuned it to be 1:1 on 15m. It’s less than 2:1 on 20m and 40m and easily tunes 6m and 17m.