I made my rinse tank
it's about 12" x 4.5" x 10", which holds several meals+snacks, or, you know, my rig and a couple lights
This is my little lunch bag:
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Which I mostly got because it was cute, but it conveniently fits my housing, strobe, arms, clamps and tray (I'm really good at Tetris). I almost always get flagged going through security, so if I don't feel like chancing it, I'll pull that shark bag out and send it through separately. Otherwise, when my bag gets kicked out and they ask if there are any fragile items, it's super-easy to point the TSA folks to the shark lunch bag in the middle of my backpack