In most cases the card medium is a composite "sandwich". The core may be paper or a plastic which can be imaged using proprietary office printers (usually modified). This core is then encapsulated with a clear plastic to enhance security and provide a durable product.
A variety of additional security devices will be used: secure inks, the printed design, OVD and holograms, embossing, machine readable devices including barcodes and OCR. All of these will serve to enhance the efficacy of the card and reflect its generally accepted 10 year life.
Euclids card based remit was extended in 1999 to include documents of security. This reflects the fact that many security document based solutions are now including traditionally card based media such as smart passports and electoral cards.