Sorry to keep commenting on an old post but some solutions I have been considering--
- the larger one-way air deflectors that fit on larger vents, but serve this exact purpose, might be an option: https://www.amazon.com/Elima-Draft-Commercial-1-Way-Deflector-Diffusers/dp/B01BWZ90HK
- there are other commercial "linear" air diverters that could be indicated potentially
- you could get a pack that overlap and cut a hole in one side: https://www.amazon.com/dp/B0994NQ3MM/ref=sspa_dk_detail_2?psc=1&pd_rd_i=B0994NQ3MM&pd_rd_w=g2BkG&pf_rd_p=0c758152-61cd-452f-97a6-17f070f654b8&pd_rd_wg=IKvvO&pf_rd_r=1S1QGF99H4BSFPRWN0NE&pd_rd_r=274d6c18-e82d-42c4-a40a-883c3f4a5705&s=hi&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEySzVKWFBUQlJXRkJWJmVuY3J5cHRlZElkPUEwMjMzNDM5MjFKWko0VlNWSFM5NSZlbmNyeXB0ZWRBZElkPUEwOTcyNTY4M0pJQVdWUDJRUkdTNiZ3aWRnZXROYW1lPXNwX2RldGFpbCZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=
for folks with floor vents:
- you could just use the under the bed diverters even though they are unnecessarily large and jsut orient them the other way, affixing them to the carpet