Here is a KIB rig that I put together using all items that can be found at a Lowe's for under $20.00. It's quite functional and easy to make.
Essentially, the moat is the "upside down" rim from a large planter/small fish pond called a "Plantainer" and the hoop/wand is made from flexible PEX plastic plumbing tubing and connectors.
The images should be self explanatory.
Simply cut the rim off off the tub using a dremel, snips, heavy duty shears, or whatever you have that will cut a clean straight line around the tub, separating the rim from the bottom.
Make sure that you leave at least as much depth to match the outside edge of the rim. That's the moat.
Then you take 2 lengths of the flexible plastic tubing and measure and cut it to make a loop/wand with a short handle. Use the connectors (Along with a small screw. This is not shown) to fasten the pieces together. It worked well without any string around the wand, but I ended up wrapping it with cotton twine and it works much, much better.