I read this thread with great interest since I just set up a second 1000-gallon ray pond and I needed to move 2 large castexi females into it. One of them is 24" disk, the other is 22" disk. In the past I've used both the rubber net method and the container method. These rays are too heavy for me to pick up by myself safely (I'm a girl), plus last time I used the rubber net on them, it bent from the weight. I also want to mention that it seems to vary from ray to ray on how calm they are during moving. One of these castexi is very calm and the other is very timid and freaks out easily.
I'm very experienced moving large koi (up to 36"), so I used a similar method to what I do with koi. I have a 30" koi net and 30" koi bowl and I got a friend to help me move them last night. It went amazingly well! Under 8 minutes to catch and move both of them. I slid the net under the ray, then gently lifted and had my friend slide the bowl under her. I slid the ray into the bowl and gently poured out most of the water. I put a towel in the water over the ray to pad the barb if it did thrash (plus I thought it might calm them a little to be covered). My friend and I then lifted the bowl and put it in the new pond, which was very close by.