Saving the original covers for your brushes is a good idea; they help to keep the brushes’ shape when you store them. If you threw out the covers, you can still make yourself new ones from paper — or you could buy these cool magnetic covers from Whitney Innovations.
The breathable, waterproof cover allows the brushes to dry while holding their shape during storage. The adjustable cover uses a Velcro catch to fit both straight and angled 3-1/2″ brushes. The coolest part is that the cover has an integrated magnet for hanging the brush on metal surfaces.
The copy on the site is written like a Babelfish translated it from English to some other language and back again, so we can’t tell exactly if you get one or two covers for $10, not including shipping. This seems rather expensive for a brush cover. If they could price them at $2 a piece — and actually sell them someplace you’d actually shop — they might really have something.
Magna Catch Brush Cover [Whitney Innovations]