Eighty years ago in the U.K., there was a war going on, which meant that many Christmas presents might have been unavailable. But Britons were known for keeping a stiff upper lip, and if there were no gifts in the shops, then they could make their own.
This ad for Pyruma putty cement appeared in the December 1943 issue of Practical Mechanics. After making the model, you baked it in the oven and it became stone hard. The compound was also used by the military in making models.