So I used the "LST Plant Training Clips" by RQS. And it works great for lst. But I broke two branches when removing the clips, and damaged almost all the others ... The clips are super rigid, and will damage the branches if they are too big. Or, just break the branches if they're too small. The main culprit is the small "lip" that protrude on each side. It slices the plant, and there isn't much you can do about it. (And yes, I was slow and careful, didn't help.) Softer clips would work the same, with fewer chances to damage the plant.
It's a shame because they work great for LST. I'll look for better/softer clips.