Now I've removed the drivers for final finishing. Here's one speaker after the application of Elmers wood putty. Apply it to all the imperfections, give it a day to dry, then sand it smooth. Be sure to coat the mdf ends so they won't soak up the paint.
The painted speakers waiting for driver reinstallation. The EZ way to paint speakers is to roll it on. I prefer Rustoleum American Accents paint. It's available in a quart size can which is adequate for a pair of speakers. Using a smooth 4" long roller, apply three or four coats about a half hour apart. This vinyl based paint drys quickly, but it remains a bit tacky for a month or more, so don't place any heavy objects on the speakers for a couple of months or they will mar the finish.
A completed speaker