Here are some pictures of my vents

The foam I used

The finished product

That looks like it might be 1/8" thick material. Is it, or do my eyes deceive me? Is it really soft or does it have some compressive resistance? In any case, who's the supplier and, ideally, what's the part number?

I believe this is what I ordered

https://www.amazon.com/dp/B09YGXQM2X?ref_=ppx_hzod_title_mob_b_fed_asin_title_1_0

Thanks ever so much, Patcon. I've order some of the 2 mm material. Because it's foam, the extra thickness shouldn't pose a great problem.

Got the foam and my vents now look like those in Patcon's pix above. Looks like good sealing all around (as much as can be expected considering you can't seal at the pivot points), yet, when I suck on the vent outlets, there is air sneaking past the seals. I guess I'll just have to see if it's annoying when the car is back on the road.