Innovation also extended to Birmingham's products, which were increasingly tailored to its merchants' national and international connections. During the first half of the century growth was largely driven by the domestic market and based on increased national prosperity, but foreign trade was important even in the mid-century and was the dominant factor from the 1760s and 1770s, dictated by the markets and fashions of London, France, Italy, Germany, Russia and the American colonies. The adaptability and speed to market of the Birmingham economy allowed it to be heavily influenced by fashion – the market for buckles collapsed in the late 1780s, but workers transferred skills to brass or button trades. Birmingham manufacturers sought design leadership in fashionable circles in London or Paris, but then priced their goods to appeal to the emerging middle class consumer economy; "for the London season the Spitalfields silk weavers produced each year their new designs, and the Birmingham toy-makers their buttons, buckles, patchboxes, snuff boxes, chatelaines, watches, watch seals ... and other jewellery." Competitive pressure drove Birmingham manufacturers to adopt new products and materials: the town's first glasshouse opened in 1762, manufacture in papier-mâché developed from the award of a patent to Henry Clay in 1772, foreshadowing the Birmingham invention of plastics the following century, the minting of coins grew from 1786.