The 17th century was a time of great change in the world. It was a time of political and intellectual revolution. New lands had been discovered and were being explored. Regimes fell, and others rose and power changed hands. The stories of that time are still being told and the costumes worn still hold a sense of romance and adventure.
A common sailor on a pirate ship could wear a striped shirt and a pair of dark trousers cut off to about mid-calf. Wrap a colourful sash around the waist to tuck the sword in and tie a kerchief around the head. Go barefoot. For the captain, wear a long vest over a white shirt. Wear a sash and sword over the vest. Pin a wide brim hat into a tri-corner hat and add a large feather. Wear pirate boot covers from a costume shop over regular shoes or add a big faux leather cuff to a pair of boots form the thrift store.
Make the tunic by cutting two bright blue panels as wide as your child's shoulders and the length from shoulder to mid-thigh. Trim them in gold and paint or sew a gold cross to the front of one. Sew them together at the top leaving a gap for the head to go through. Wear this over an oversized or poet cut white shirt. Add gold buttons down the outside of a pair baggy sweat pants. Sew faux leather cuff to the tops of thrift store boots or buy pirate boot covers from a costume shop. Pin the brim of a black hat up on one side and add a large white feather. Big cuffed work gloves and a toy sword complete the costume.
Start with black sweat pants or a skirt and a black shirt. Make white cuffs and a white collar out of felt or any stiff white cloth. For a girl, add a white half-apron and a simple white bonnet. For a boy, glue or sew a gold buckle to a wide brim hat and wear a pair of white knee socks beneath the shortened sweat pants. Sew or glue gold buckle to thrift store loafers.
A Halloween princess costume or a formal from the thrift store can be transformed into a 17th century queen costume. Royalty of that day wore stiff stomachers on the bodice of their dresses. These can be can be made with a stiff triangle of matching brocade fabric. Sew it to the front of the dress from just above the bust line to a point a few inches below the waist. Seventeenth century queens were also fond of high stiff collars. Make one from the same cloth as the stomacher. Sew lace around the edge and sew it to the neck line of the dress. Buy a cheap crown from a costume shop and remove and replace the plastic jewels with nice glass jewels from a craft store. Wear lots of rings and a couple of gold necklaces.