Here is a good way to repurpose those flimsy old tomato cages. I tie/or tape the legs of the cage together. Then starting from the bottom(cage inverted) wrap one level of the cage at a time w/plastic wrap then use a few pieces to tape to secure. Use tape to attach levels to each other and seal any gaps between them. Leave a small opening on top for fresh air venting, and adding humidity with mist from a spray bottle if needed.
I have been getting young trees in the mail and up potting them so they are tucked into a new home for next year. They all seem to have rust or other fungal issues when they arrive from the time in the box. I soak them down with Safer sulfur spray and give them a week in the tent, then a few days of increasing time without the tent on.
My first tree I received in the mail was in severe danger of total leaf drop, it took me a few days of various methods of tents before I came up with this. I think the sulfur spray is huge as well, I didn't use this at first either and the rust was having it's way with the leaves. The first tree lost about 60% of its leaves before I figured it all out. The second tree (which is now out of the tent) went straight into the system and so far has lost one immature leaf which could have just been damaged in shipping.
I apologize for the sideways picture, it's upright on my end but after uploaded it turns sideways. The second picture just shows how I used a couple pieces of tape to close the top and leave a small opening on each side.