According to this, we would probably be looking at 24" wide windows in the posted example. The height is about 2.5 widths (by pinched finger approximation on the image), so we will choose 24x60 from the standard matrix.

20" width maximum, so you will have to fold over on side to pull this off as a single panel. Fold in only the 4" you absolutely must, and that leaves you with 16" you can engrave in one shot, and 8" in the second shot. Split the difference for even halves and you are folding in 6" each time, to enable engraving of the left or right 12" in each go.

Now, if your material is only 3/16" thick, you can use the passthrough for this and not worry about the other dimension. But I don’t know if 3/16" is adequate for blackout results. So I will assume it isn’t and anyone who does this will have to fold for height as well as width.

To get 60" into the 12" available will take quite a few more segments, and likely many folds. Let’s assume you work in 5" segments, so that removes your front 5" from available work space and leaves you with the back 7" (PRU crew… can you confirm at least 5" of available space behind the honeycomb? Sounds semi-reasonable, but possibly too large)

So, to engrave the top of the curtains you would need to have 10 folds worth of material rolled up in the front end. Absolutely would have to be a roll, since folding 10 times doesn’t exactly work with most materials.