oh gramps,
for us tomato cagers i did figure out a really killer 0% stress guaranteed way to train the plants. its also super cheap too.
So you need tomato cages and that green gardeners tape. All you do is drape a really long piece over the stem then pull both ends of the tape down and tie it to the tomato cage.
This method works way better then string, or zip ties, or pipe cleaners because it cannot dig into the branch, it does not slip, itwill never choke the stem from growing bigger as you dont actually tie anything around the branch, and it has some bounce so it holds up in the wind and lets the plant move naturally.
Ill see if i can make a diagram or pic later, but this way just seemed so nice, especially for larger plants. I was having no probs bending down stems like half an inch thick.