An Etui (pronounced a-twee) is a pocket-sized ornamental case dating from the 18th to 19th century. These cases were made of different materials, such as silver, gold, enamel, gilt metal and tortoiseshell.
See image 1 of an 18th century Meissen style porcelain etui (image courtesy of Times Past Antiques, http://www.goantiques.com/detail,gilt-banded-18th,
Etuis had fitted interiors containing various small useful items, such as writing sets, scent bottles, knife, fork and spoon sets, and sewing accessories. Others contained just about everything.
See image 2 that shows a mid 18th century Georgian Etui Necessaire. The front and back of the tapering case is decorated with various musical instruments and foliage, on a stippled background. The interior is fitted with 11 implements, including fork, two knives, measure ruler, scissors, ivory leaves, snuff spoon, tweezers, file, and a needle threader. (Image courtesy of Louis Wine Antiques, Toronto, Canada http://www.rubylane.com/item/598821-L1758/Georgian-Silver-Etui-Necessaire-circa
See this example (image 3). It is a circa 1840 bloodletting etui with four tortoiseshell covered lancets. The instruments are known as thumb lancets due to the way in which they were held and pushed into a blood vessel! (Image courtesy of Alex Peck Medical Antiques, http://antiquescientifica.com/archive2.htm)