Rigid, high-flow, taco-style 4x5 sheet film developing cages?
Made from Frost-King Gutter Guard plastic mesh. Supplied in 6-inch by 20-foot rolls, it's designed to act as a leaf filter over your rain gutters.
It's a quarter-inch mesh that, when suitably trimmed down, can provide a perfect enclosure to allow processing solutions to access both the front and back sides of negatives. This is especially useful in facilitating the removal of anti-halation dye since it prevents the film back from being pressed against other sheets or the tank wall. It works much better than window screen for this because of the thicker gauge and much larger mesh openings.
Just trim off a 5.75-inch length piece from the roll. Then trim the original width down from 6-inches to 5.5-inches. Set up a small flame of some sort. I used a small propane torch (burner) adjusted to the lowest flame. Gently and evenly pass the sharp trimmed edges of the mesh through the flame. They will quickly melt and recool, smoothing the sharp-edged cuts in the process.
Then fold the mesh over along the length dimension and secure the edges using four small plastic cable ties. I used Thomas & Betts SF100-18XC ties because they are designed not to expose the sharp edges common to this class of product when the excess length is clipped off. Plus they are black, so they look cool.
Voila! A chemically inert, reusable, taco-shaped protective cage for your negatives.
I have found it extremely easy to load these cages in total darkness. The sheets slide in quickly and smoothly. And once inside, the film is completely protected. Three of these will comfortably fit into a 4-reel stainless steel developing tank, thus allowing you to use your regular inversion protocol if you wish. And keep you from having to spend US$200+ on a Nikor 4x5 tank...