I found these hydroponics pots and I'm 95% sure they're going to be perfect! I hope so because I bought 100 of them...I'm a sucker for good value
. I figure that's about a lifetime supply if they work out. They're a little bit bigger than I would've preferred, but that was the smallest I could find to give me enough depth for large VFTs. They're approximately 5" x 5" x 7" and have a 1 quart capacity. Also nice that they're white so I can use them indoors or outdoors (not sure how they'll hold up to UV, though).
I'm excited to finally be able to have all my plants in identical square pots. They'll save so much space and be so much easier to water. Now I just need to find some flood tables they nicely fit into.