Solid rear window?

Des anyone know of a company etc that make a single piece rear window to fit onto a truck cab for a defender?

Hve seen a few cabs on ebay with them fitted and wondering if someone makes them or its just a case of sheet of Perspex and a jigsaw or a friendly window company and some claytonrite

landyglass do one i had a look at them at the donnington show!

£99.00 i think

lee