I couldn't be bothered to get a proper window insert material, so I thought: Why not print it? Obvious.

And to avoid the milkiness that comes with more layers, I reduced the actual see-through parts of the window to a single layer. 

The good news: It kind of works. You can see… something.

The bad news: The print quality of my example is surprisingly bad. I printed this with ironing on the smooth PEI sheet and it's barely better than the same thing printed on the satin sheet without ironing, all while being substantially slower, much stringier, more burnt and harder to get off the plate. In short: I'll go back to my default settings. They're good enough for me and better than an opaque lid.

I'm using this with the snap-in grid lid (https://www.printables.com/model/1076885-modern-gridfinity-case-snap-in-window-and-more), not sure how well it works with the default one.

I only made the 5x4 window that fits on the MK4's bed. They're all 1mm high, with the recesses being reduced to whatever the file name says. Pick your layer height.