Better-looking return air grille. Check out another DIY return air grille solution here. Do you have a baseboard return air grille that looks like this? Not especially attractive, right? I'm pretty sure o.
40 Easy DIYs That Will Instantly Upgrade Your Home
Cover up an unsightly air vent with a rubber doormat. Even easier, just put in two hooks over the vent and hand the doormat. Make sure the holes in the doormat are large enough to let air flow through.