Some of the simplest ways to make Frozen costumes without a pattern are to add either embellishments or fabric pieces to everyday clothing items. Dramatic hair and makeup styles also enhance a costume made of regular apparel.
For an Elsa or Anna costume, wrap a piece of blue or green floor-length fabric once around the waist of a white long-sleeve t-shirt, and secure it with shiny or colored duct tape. Braid the wearer's hair and add frosty makeup to complete the look.
To make an Olaf costume, glue fabric circles in the shape of eyes and buttons to a white hooded sweatshirt, and attach pipe cleaners to the hood for hair. Stuff the sweatshirt with cotton batting once it is on, and make a carrot nose from orange fabric for the wearer to hold.