I rarely go there, but I couldn't wait to get to WalMart this morning! Picked up a half-dozen of those hanging mesh trays (couple smalls, couple longer). I was going to start, tomorrow in fact, making some more add-on boxes and MFT add-ons. These are certainly a lot simpler and actually more space efficient don't lose space for the thickness of plywood).
I did some test fitting on my 1080s. The trays hang quite nicely off the side track profile. They're just 'hanging", but wouldn't fall off unless you bumped them pretty good. They do NOT fit on the top lip. It is about 1/2MM too thick.
The side profile is a sweet convenience, as you can just hang them in place, without having to slide them down the length of any side. In other words, the height of the tray's lip is shorter than the space in the MFT profile, so you can just attach it anywhere. I will probably use a bolt, as they'll be "permanently" attached since I don't move the MFTs.
Thanks Qwas for posting about your bench build, which led to the older thread by Benchdog related to those trays! I found it funny someone mentioned they would make good Qwas "dog house", as one of the shorter trays is 90% going to be the spot for my Qwas dogs.