Nice build! I remember when they used to sell those things years back. If you wanna go bigger, get some WaterHeater pans. They go as large as 24" across, just make sure you get the rubbery ones. The cheap ones are brittle plastic... They should run about $12(+/-) for a 24"
Oh, they do go as small as 18" also...
And they will have a drain hole in them that you can duct tape over or use the drain with pipe if you want inside the home. Years back we used the pans with our screen cages to collect the water when the cages were inside the house. The drain is handy to go into a bucket or link multipule drains up to go into a bucket or outside.(Just remember to elevate the cage above the pan bottom.)
The ones I used for top and bottom at the trays for under plant pots. They are about 20" across for I think $8 a piece. Then under the bottom one I cut a piece of plexiglass the diameter of the tray to helps support weight.
Back when I was first going to get my first cham, I was attempting to build a PVC pipe cage, which ended up costing me over 100 dollars before I even bought the mesh screen! So I abandoned that idea and went with a large reptibreeze...that I have had to modify a ton to suit my needs. To this day, I still don't understand why screen cages are "the best". Our chams need airflow, which a screen cage provides, but they also need humidity, which a screen cage does not...
In my opinion, screen cages work best outdoors, and glass or acrylic style works best indoors.
I just took Weirdo outside for the first time in a while earlier today, and he got so green and happy looking and really enjoyed being outside, so I think that will become something we do more in the future, mostly with the help of his new outdoor cage I plan on building. (I will probably make it huge using the waterheater pan idea that was mentioned earlier).