In earlier centuries, samplers were a way of passing patterns on and of practicing stitches and techniques. Today samplers are a fun way to try out new patterns and color combos as well as becoming works of art in their own right. Sampler possibilities include books, wall hangings, throws, mats, shadow boxes (for 3-D crochet pieces), other art pieces. This could be Irish crochet motifs, filet crochet, hyperbolic crochet in a shadow box, granny squares, amigurumi in a shadow box, etc.
Sampler Book - Belgium
This could be a way to display crochet sampler pieces. Liz Cooksey - Textitle Artist - Gallery II - crochet and fiber art
Liz Cooksey - Textitle Artist - Gallery II
Ravelry: Ariadne Scarf pattern by Dora Ohrenstein. This is a "sampler" scarf which is a study in how different hooks and yarns behave and drape.
Romanian Point Lace Crochet sampler butterfly in the January/February 2001 issue of PieceWork magazine.
Needle Lace Sampler. Could be done using crocheted cords and needle weaving fillings as in Romanian point lace crochet work. lynxlace.com