Portals are created by bending space and time with the aid of magical entities, fairy dust being the most commonly used aid.
Portal Gating is a branch of study in the great tree of magical wisdom, and the mages who specialize in portal creation are known as Portmages.
The Blender which Agent Klein uses in Jackson Kross and the Dragon Girl is a device with pre-loaded spell algorithm that aid in short distance teleporting.
The fairy dust required for teleportation shot up exponentially as the weight increased, meaning that a one-fifty pound man would need about ten pounds of dust. For that they would need a larger device than a pocket watch, and a larger area of operation.
It was for this purpose the Teleporches were invented, the finest of which were created and operated by the Imperial Teleporch Service, a part of the Sovereign Passportal Office.