I do have two small additions to this one!
1) If you want the groove to be a bit further from the edge (for whatever reason - bigger overlap in the doors, etc.) you can add a "guide-ridge" to the card, like so:
2) If the silicon ridge is too big (and seals completely) the other glass door will get smudged or the doors will be too difficult to open. If it is too small / just right then you will still get some FFs that escape, especially smaller ones.
SO, to avoid the smudging and for added FF-proofing, I've recently started adding a
SECOND ridge on the other door, like this:
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V
^__
It's barely visible once closed but definitely helps with keeping in FFs. In the pic below you will see two ridges - they are both pointing at each other so will actually press against each other when the doors are closed leaving literally NO gap. When they are open they do not touch the other pane, therefore no smudges / easy to open. Don't mind the terribilis...