The Shell Hexagon Cardigan is a bold yet elegant garment created using classic hexagon construction combined with a striking shell stitch pattern. With its flowing drape, rich texture, and fully customizable fit, this cardigan feels both whimsical and wearable. Whether you love oversized sleeves or prefer a more tailored silhouette, this design adapts effortlessly to your personal style.
The cardigan is constructed from two large hexagons that are extended, shaped, and joined to form the sleeves, body, and neckline. Once the base hexagon is complete, the construction becomes intuitive, making this project both enjoyable and deeply rewarding for adventurous crocheters.
What truly sets the Mermaid Shell Hexagon Cardigan apart is its versatility. The hexagon structure allows for easy adjustments at every stage, from sleeve width to overall length, making it suitable for a wide range of body types and style preferences. The repeating shell stitches add beautiful movement and texture, especially when worked in gradient or mermaid-inspired yarns, turning this cardigan into a standout handmade piece.
Shell Hexagon Cardigan
Skill Level
Intermediate
Confident beginners may also enjoy this pattern if they are comfortable working shell stitches and basic garment construction.
Materials
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DK weight yarn
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Main color (shells / “mermaid” color)
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Contrast color (between shells / structure color)
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Crochet hook suitable for DK yarn (example: 5.0 mm / H-8)
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Stitch markers
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Scissors
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Yarn needle
Yarn Notes:
Smooth or lightly variegated yarns showcase the shell texture best. Color-changing yarns work beautifully for a mermaid-inspired effect.
Gauge
Gauge is not critical for this garment.
Fit is adjusted by adding or removing rounds.
Finished Size
Fully customizable
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Increase or decrease the number of hexagon rounds to adjust size
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Sleeve and body length are added after assembly
Stitch Abbreviations (US Terms)
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ch – chain
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sl st – slip stitch
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sc – single crochet
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dc – double crochet
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hdc – half double crochet
Pattern Notes
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The cardigan is constructed from two hexagons
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Each hexagon has six corners
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Corner stitches are always worked into the same corner spaces
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Shells are made with 7 double crochets
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Single crochets anchor the shells and control spacing
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Stitch markers are highly recommended to clearly mark corners
HEXAGON MOTIF
Round 1 – Center
Ch 5 and join with a sl st to form a ring
(A magic ring may be used if preferred.)
Work a stacked dc or ch 3 (counts as dc).
Ch 2, dc into the ring, ch 2.
Repeat dc, ch 2 until you have 12 dc total, each separated by ch 2.
Join with a sl st to the top of the starting dc.
Round 2 – Shell Setup
Switch to the shell color (if using two colors).
Attach yarn in any ch-2 space.
Ch 1, sc in the same space.
Shell Pattern:
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In the next ch-2 space: 7 dc
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In the next ch-2 space: sc
Repeat around for a total of 6 shells.
Join with a sl st to the first sc.
Round 3 – Corner Formation
Switch to the contrast color.
In each sc between shells, work the following corner:
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dc
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ch 2
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dc
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ch 2
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dc
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ch 2
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dc
(4 dc with ch-2 spaces between)
Between corners, ch 4 or ch 5, keeping it consistent throughout the round.
Join with a sl st.
You should now have six clearly defined corners.
Round 4 – Shell Expansion
Switch back to the shell color.
In each corner:
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7 dc
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sc
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7 dc
Between corners:
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sc in the top of each shell
Join with a sl st.
Continuing the Hexagon
Repeat the following rounds:
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Contrast color rounds: work corners into corners, using V-stitches or dc placements along the sides
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Shell color rounds: work shells into V-spaces with sc between shells
Continue until the hexagon reaches the desired size.
Fold the piece in half occasionally to check sleeve depth.
Typical adult size: 20–24 rounds (adjust as needed).
Make two identical hexagons.
CARDIGAN ASSEMBLY
Fold & Join
Fold each hexagon into an “L” shape.
Align the back panels and join them using slip stitches or a join-as-you-go method along the back seam.
This creates:
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Sleeves
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Front panels
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Back panel
EXTENDING THE BODY
Bottom & Front Extensions
Attach the contrast color along the bottom edge.
Work V-stitches (dc, ch 2, dc) evenly across.
Turn and add shell rounds on top.
Repeat until the desired length is reached.
SLEEVE EXTENSIONS (Optional)
Extend sleeves using the same method as the body.
To taper the sleeves:
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Skip stitches
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Use slip stitches to gradually reduce the circumference
FINISHING OPTIONS
Scalloped Edge
Finish with a shell round worked evenly around the entire cardigan.
Ribbed Edge (Optional)
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Work one round of sc evenly
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Switch to a smaller hook
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Ch 6 and work sc in back loops only
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Sl st into the base every two stitches
Repeat for cuffs, hem, and neckline.
Blocking
Steam blocking is highly recommended.
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Do not stretch the garment aggressively
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Steam relaxes the fibers and enhances drape
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Always test steam on a swatch first
The Mermaid Shell Hexagon Cardigan is a true statement piece that blends classic construction with modern texture. Once you understand the hexagon logic, the pattern becomes intuitive and endlessly customizable. Experiment with color choices, sleeve length, and edging styles to create a cardigan that is uniquely your own.
