the church. By the 15th century there was an industry exporting Nottingham alabaster altar reliefs in groups of panels over much of Europe for economical parishes who could not afford stone retables. Small carvings, for a mainly lay and often female market, became a considerable industry in Paris and some other centres. Types of ivories included small devotional polyptychs, single figures, especially of the Virgin, mirror-cases, combs, and elaborate caskets with scenes from Romances, used as engagement presents. The very wealthy collected extravagantly elaborate jewelled and enamelled metalwork, both secular and religious, like the Duc de Berry's Holy Thorn Reliquary, until they ran short of money, when they were melted down again for cash. Renaissance Renaissance sculpture proper is often taken to begin with the famous competition for the doors of the Florence Baptistry in 1403, from which the trial models submitted by the winner, Lorenzo Ghiberti, and Filippo Brunelleschi survive. Ghiberti's doors are still in place, but were undoubtedly eclipsed by his second pair for the other entrance, the so-called Gates of Paradise, which took him from 1425 to 1452, and are dazzlingly confident classicizing compositions with varied depths of relief allowing extensive backgrounds. The intervening years had seen Ghiberti's early assistant Donatello develop with seminal statues including his Davids in marble (1408–09) and bronze (1440s), and his Equestrian statue of Gattamelata, as well as reliefs. A leading figure in the later period was Andrea del Verrocchio, best known for his equestrian statue of Bartolomeo Colleoni in Venice; his pupil Leonardo da Vinci designed an equine sculpture in 1482 The Horse for Milan, but only succeeded in making a clay model which was destroyed by French archers in 1499, and his other ambitious sculptural plans were never completed. The period was marked by a great increase in patronage of sculpture by the state for public art and by the wealthy for their homes; especially in Italy, public sculpture remains a crucial element in the appearance of historic city centres. Church sculpture mostly moved inside just as outside public monuments became common. Portrait sculpture, usually in busts, became popular in Italy around 1450, with the Neapolitan Francesco Laurana specializing in young women in meditative poses, while Antonio Rossellino and others more often depicted knobbly-faced men of affairs, but also young children. The portrait medal invented by Pisanello also often depicted women; relief plaquettes were another new small form of sculpture