Kidney shape – make 2 for each kidney

Cast on 3

Row 1: Purl

Row 2: Knit, increasing in each end (5)

Row 3: Purl

Row 4: Knit, increasing at each end (7)

Row 5: Purl

Row 6: Knit, increasing at each end (9)

Row 7: Purl

Row 8: Knit

Row 9: Purl

Row 10: Increase in first stitch, knit to last 2 sts, k2tog (9)

Row 11: Purl

Row 12: Increase, knit to last 2 sts, k2tog (9)

Row 13: Purl

Row 14: Knit

Row 15: Purl

Row 16: K2tog, k to last st, increase (9)

Row 17: Purl

Row 18: K2tog, k to last st, increase (9)

Row 19: Purl

Row 20: Knit

Row 21: Purl

Row 22: K2tog, k to last 2 sts, k2tog (7)

Row 23: Purl

Row 24: K2tog, k to last 2 sts, k2tog (5)

Row 25: Purl

Row 26: K2tog, k to last 2 sts, k2tog (3)

Cast off purlwise, fasten off.

With wrong sides together, whipstitch around the edge and stuff.

Optional – leave one side open and add felt or fabric and a mesh to demonstrate filtration.