I need to transport some cactus and I am using plastic tubing wrapped around key locations to structurally support the cactus and lift it up. To make this much more useful, I would like to find a simple tightening ring that I could slide down the plastic tubing so that it tightly wraps the cactus. This idea is very common in eyeglasses, where straps will loop around the back of the neck, and a slider ring can then be brought in along the straps to tighten against the neck. See the photo below.

In my case, I have 1/4 inch plastic tubing (and eventually larger tubes), and those are loosely looped under a side of the cactus and then the ends are pointed up to the sky. I want to wrap a tightening ring down around those two tubes close to the cactus, so it cannot slide off. The cactus can then be easily lifted using the far ends of the tubing, which are long enough to keep your hands far away from the cactus.

Of course, there are many tightening rings available for plumbing applications, but those require you to screw down the ring. For a permanent install that is sensible, but for my application, it is too much work. I want a ring I could easily slide down the tubes or manually tighten around the base of the tubes. Is there a simple tightening ring I can use for my case?