A reusable air filter and methods are provided for filtering air being conducted to an air intake of an internal combustion engine. The reusable air filter comprises a filter medium configured to pass an airstream and entrap particulates flowing within the airstream. The filter medium is comprised of cotton gauze disposed in a sinusoidal arrangement that provides a filtration surface area that is larger than a perimeter area of the filter medium. An end cap and base may be configured to retain the filter medium therebetween. The base provides an interface between the air filter and an air inlet of the engine. The filter medium may be disposed in a flat, panel shape that is bordered by a supportive tray. Support rods may be embedded within the tray to prevent bowing of the tray due to air pressure when coupled with an air box of the engine.