You can paint our Smart Vents, by the way! That's something you definitely can't do with other smart vents that use cheap plastic faceplates. Ours are powder-coated steel!
Here are some hints we've shared with customers on how to paint our faceplates. The vent faceplates are all powder coated. To ensure that a new coat of paint adheres to the vent, we recommend lightly sanding the surface with 60-grit followed by 180-grit sandpaper. Make sure you wipe off all the sanding dust before applying primer coat to a very small area on the vent. Be sure to use a primer meant for steel.
Wait 20-30 minutes for that primer coat to surface dry and rub it to see if it's adhered to the surface. If it has, then you're good to go to prime the rest of the faceplate before painting it. If you're using a paint+primer spray paint (such as Rustoleum), then you will not need to prime.