Capsules are provided for holding material within a vaporization chamber of a personal or portable vaporization device. Each capsule comprises a cap and a cup, each with a corresponding base wall having air inlet/outlet holes therein. The capsules are provided with first and second standoff structures that position the respective capsule to avoid occlusion of the air inlet/outlet holes by surfaces of the oven and/or lid that form the vaporization chamber. During use of the vaporization device, the capsule design encourages air to flow through the material held within the capsule via the air inlet/outlet holes, rather than flowing around the capsule to bypass the material held therein. In some embodiments, the capsules include tamper-resistant features that prevent separation of the cap and cup once assembled, thereby protecting the material held within the capsule.