A mobile client device, such as a wireless mobile or a palm sized personal digital assistant, is provided with a number of sensors and companion programming instructionscircuitry to generate a heart rate reading for a user holding the device. A portable data carrier has an interface for sending and receiving data, data memory for storing received content data, and payment validation memory for providing payment validation data to an external device. The final shape of the container can then be achieved by igniting an inflammable gas injected into the container, whereby the combustion generates a higher blowing pressure, or by injecting an additional gas with a higher blowing pressure of approximately 40 bar into the container after pre-blowing.