This is from an old NMAH exhibit, but I thought I'd post it anyway. They displayed the portable lap desk that Jefferson used to write the Declaration of Independence:
Jefferson designed the desk while a delegate to the Continental Congress in 1776, and had it built by a Philadelphia cabinetmaker. The "writing box," as he later called it, is of mahogany, and of modest size: 9 3/4 inches long by 14 3/8 inches wide by 3 1/4 inches deep. There’s a folding board, lined with green baize, attached to the top—when it is opened, the writing surface grows to 19 3/4 inches. A drawer in one end of the desk has space for paper, pens and a glass inkwell. The whole is about the size of an attaché case—barely larger than the first generation of laptop computers in our own day. But this 18th-century think pad, at least, earned the name.