Widely regarded as the “Cadillac of Vaporizers,” the German-made Volcano uses convection to make vapor, which is then collected in food-grade bags, much like balloons being filled with air. Depressing a specialized mouthpiece allows you to inhale the vapor, while keeping the unused portion within the bag.
The most hygienic approach is to wipe down the mouthpiece with an alcohol swab before use and to not place your mouth directly on the mouthpiece, instead, depressing it with your finger while inhaling. There are several versions of this type of very efficient vaporizer on the market today, including those with distinctive and stylish stainless steel finishes and digital temperature displays, but they tend to be pricey (around $500-700) and the forced air system does make noise similar to a blowing fan.