Rhombus Cube Quilt Tutorial: Jenny Doan's Stunning 3D Tumbling Blocks Design

🧵 Light fabric — 2 yards (Jenny used light gray Cotton Couture by Michael Miller). Shop fabric.

🧵 Medium fabric — 2 yards (coral/medium value). Shop fabric.

🧵 Dark fabric — 2 yards (dark gray). Shop fabric.

🖼️ Border fabric — 1½ yards (black — makes the quilt "float"). Shop fabric.

📐 Rhombus template — a 60-degree rhombus quilting template. Shop rulers & templates.

✂️ Rotary cutter, ruler & cutting mat — for precise 5" strip cutting. Shop rotary cutters.

📌 Pins or clips — for matching seams in vertical columns. Shop pins & clips.

🪡 Sewing machine with ¼" foot

Step 1: Cut Your Fabric Into 5-Inch Strips

Start by cutting all three fabrics (light, medium, and dark) into 5-inch strips across the width of the fabric. You'll need plenty of strips — roughly 8–10 from each fabric depending on your quilt size.

Open each strip up to its full single-layer width (don't leave it folded). This is important because you'll get more rhombus pieces per strip when cutting from a single layer.

Step 2: Cut Rhombus Shapes with the Template

Place your rhombus template on the 5-inch strip and cut your shapes. The template has a 60-degree angle that creates the perfect parallelogram for the tumbling block effect.

Cut rhombus pieces from all three fabrics — you'll need equal numbers of light, medium, and dark pieces. Expect about 10 rhombuses per strip. Keep them organized in separate stacks by value.

Step 3: Add Corner Triangles to Eliminate Y-Seams

Here's the magic of Jenny's method: instead of sewing Y-seams, you'll attach small 60-degree triangles to the edges of your rhombus pieces. These triangles fill in the gaps so you can sew everything in straight vertical columns.

Cut 60-degree triangles from your medium (coral) fabric. Lay them right sides together with the rhombus pieces — the little notches on the template will line everything up perfectly. Sew with a ¼-inch seam allowance.

Important: The light and dark rhombuses get their triangles on opposite sides. All your darks go in one direction, and all your lights go the opposite direction. This is what creates the cube illusion when assembled.

Jenny shows how the rhombus pieces and triangles come together to form the cube illusion.

Step 4: Arrange the Cube Pattern

Now comes the fun part — watching the 3D effect appear! Lay out your pieces to form the tumbling block pattern:

Arrange your pieces in vertical columns. In the first column: coral triangle, light gray, coral triangle, dark gray — alternating. In the next column: coral triangle, dark gray, coral triangle, light gray — the opposite arrangement. This alternation is what creates the interlocking cube effect.

Step 5: Sew Vertical Columns

Sew each vertical column as one long strip, joining the rhombus-and-triangle units with ¼-inch seams. As you sew, match the points carefully where the coral triangles meet the light and dark pieces — this is what keeps the cube pattern crisp and aligned.

Step 6: Join the Columns Together

Once all your vertical columns are sewn, it's time to join them side by side. Pin or clip at each intersection where the coral triangles meet, then sew with a ¼-inch seam. Press seams in alternating directions for each column so they nest together neatly.

The key to the 3D illusion holding up is precise matching at the intersections. Take your time pinning — it's worth the extra effort when you see those cubes pop off the surface of your quilt!

Step 7: Add the Border and Finish

For the border, Jenny uses 1½ yards of black fabric, which creates a striking frame that makes the cube pattern appear to float. To handle the edges, attach black triangles along the border row first, then trim to create a straight edge for your border strips.

Attach your border strips (cut to the appropriate width for your quilt) and press. Then layer with batting and backing, quilt as desired, and bind to finish your masterpiece!

💡 Value is everything: Photograph your three fabrics in black and white (use your phone's filter). If you can clearly see three distinct shades, you're golden. If two look similar, swap one out.

💡 Stay consistent with direction: The trickiest part is keeping all your light rhombuses angled one way and darks the other. Label your stacks and double-check before sewing.

💡 Press carefully: Press seams toward the darker fabric to prevent show-through. Use a dry iron for precision on these angled seams.

💡 Design wall magic: If you have a design wall, lay out several columns before sewing. It's much easier to spot a flipped piece before it's stitched in.

💡 Try different color stories: Solids give the crispest cube effect, but you can use prints as long as their values are clearly distinct. Batiks work beautifully for this design!