There is a gap in the market for childrenswear garments that merge multi-sizing and experimental patternmaking in self-help apparel. A gap in the market was also discovered for childrenswear inspired by the Celtic selkie myth. Pattern development for this ensemble was derived during the practice of experimental patternmaking methods: subtraction cutting. It was found subtraction cutting does not always translate proportionally for childrenswear but is successful for bifurcated garments. Multi-sizing for longer wear was successfully incorporated. Subtraction cutting did not impact fabric waste but increased fabric consumption. The amount of time and labor did not differ much from past projects. Self-help childrenswear was created with a zip-front opening for the blouse and the elasticized waist in the culottes. The Celtic selkie legend was effectively incorporated into the patterns. Digital printing provided further originality to the garment designs. The construction methods successfully contributed to the durability and quality of the garments.