Card has always been part of model railways. Buildings are still commononly made from card. Not so much rolling stock anymore. Computer controlled cutters mean that complex shapes may be quickly cut so allowing card to be used for interesting models.
Left an experimental narrow gauge locomotive body from card.
Using card for model making has been a long tradition. Today it is used mainly for buildings. The availability of hobby computer controlled card cutting machine has meant interest in rolling stock modelling from card has returned.
Trams are straight forward to make from card. There basic uniform shape means overall form can be kept simple so making card construction simple. This is more so for modern style rather than tradional style trams.
All the bodies are designed to fit over chassis liberated from existing redundant models. Many of my own designs are available to download.