Free Tutorial: Quilted Cube Case

The Quilted Cube Case is a sturdy bag that measures about 9 inches square, with a divided slip pocket on the inside and a single strap that attaches via swivel clips to the top.

Lately, I’ve been experimenting with bag designing – you may have seen some of the prototypes on Instagram. This is the culmination of prototype #3, which I felt was best suited for a full tutorial.

Here’s what you will need:

3/4″ Swivel Clips (2)
3/4″ D-Rings (2)
19″ Zipper
1.5 yards of Pellon 1-Sided Fusible Flex-Foam
3 yards of Pellon SF101 Shape-Flex interfacing
Exterior and lining fabrics (see below)

For the exterior fabrics, I used two fat quarters from Violet Craft’s Brambleberry Ridge line for Michael Miller and less than 1/2 yard of Cotton and Steel Metallic Dottie Cotton Candy.

Pellon was so kind to share some yardage from the new line of Fusible Flex-Foam, and I used the 1-sided fusible to make this bag. Full review will come later, but I can say that I was really impressed with the performance! I wrongly assumed that the fusible foam stabilizer would be exactly like the original sew-in type except with dots of glue on one side. That was not the case.

Pellon 1-Sided Fusible Flex-Foam FF78F1 is thicker and appears to be denser than the sew-in FF77.

From the Flex-Foam, you will also need to cut out the following pieces:

10.5″ x 21″
10.5″ x 23.5″
5″ x 19.5″ (cut 2)

The reason the exterior pieces are cut slightly larger is to account for the distortion in size when you quilt them. Later on, you will trim all of these pieces down.

The lining and slip pocket fabrics are Cynthia Rowley Paintbox Pin Dot Turquoise and leftover Brambleberry Ridge fabric from the gold roses fat quarter.

I used scraps again to cut pieces for the strap tabs.

Fuse the Pellon SF101 interfacing pieces to ALL exterior and lining fabrics, plus to one of the slip pocket sides.

Now it’s time to tackle the zipper. To keep the top of the zipper tape from straying, I like to zigzag stitch it together before using in a project.

Then place the zipper face down onto the right side of one of the top gusset pieces. It’s helpful to glue baste the zipper tape to the fabric in lieu of pins. Sew the zipper to the fabric – you may need to use a zipper foot to get fairly close to the teeth, but the walking foot on my Janome Horizon 7700 worked fine for me. My seam allowance was shy of 1/4 inch.

Repeat with the other side of the zipper and second top gusset piece.

This is what it should look like.

Here’s how I fused the Pellon Flex-Foam to the top gusset pieces – by placing the foam (shiny side down!) on the fabric just past where the zipper tape ends. Then I flipped them over so the fabric was on top – and ironed them on.

Despite there also being a layer of SF101 between the fabric and Flex-Foam, fusing created a strong bond with no issues.

Continue by fusing the Flex-Foam to the main panel and bottom gusset pieces.

Check it out! This stuff really bonds!

To quilt the top and bottom gusset pieces, I spaced out straight lines one inch apart. Others use a quilting guide bar attachment for a walking foot, but that just hasn’t worked for me. The method that has yielded the best results for me is marking out lines with an air soluble pen and ruler.

For the main panel, I switched things up a bit by doing diagonal crisscross lines.

When your pieces are quilted, you will need to trim them down using a rotary cutter and ruler to the correct dimensions.

For the top gusset panel, be sure to leave at least a 1/2 inch clearance on each short end past the zipper. If you don’t do this – you will have a heck of a time sewing over the zipper teeth – especially if it’s metal!

Then mark the center of each piece with a small line – this will make construction much easier later on.

We’re going to take an intermission and make the strap tabs now.

Center the interfacing onto the fabric and fuse both pieces.

Fold each long side in half an inch, and press.

Glue baste each side.

Repeat this step for each short end of the strap tabs. Then fold the long sides in half, so no raw edges are showing – glue baste again.

Slip a D-ring onto each strap tab.

Stitch a line as close to the D-ring as you can, with the ring on the center fold.

Get the quilted top gusset piece back out, and mark these lines.

Sew each strap tab to the top gusset using the lines as a guide. The strap tab’s outside edge should butt up against the line running perpendicular to the zipper. The center should be right on the line parallel to the zipper.

Okay, intermission over – back to the construction portion of this program!

Using a 1/2 inch seam allowance, connect the top and bottom gusset pieces.

Push the seam allowance TOWARD the bottom gusset and AWAY from the zipper, then top stitch about an 1/8 inch from the seam.

Here’s the best way I’ve found to construct a boxy shape:

Line up the top and bottom center marks and clip/pin working your way from the middle out to the ends of the square main panel.

Use a 3/8 inch seam allowance and sew the top and bottom sides first – stopping 3/8 inch from each end.

Clip/pin the sides and repeat sewing – stopping right at the previous stitch lines. When finished, you should have sewn a complete line around the entire perimeter of each square.

At this point, the bag exterior is finished.

With right sides together, sew together the slip pocket pieces only at the top long edge with a 1/4 inch seam allowance.

Flip the pieces right sides out, press, and stitch an 1/8 inch from the top edge.

Glue baste the side edges and bottom to one of the lining main panels.

Mark a straight line anywhere of your choosing for a pocket divider.

Starting at the bottom, stitch up to the top – then pivot your needle and sew right back to where you started. This creates a more reinforced divider that shouldn’t come loose over time. (Yes, that has happened to my bag pockets before)

On all lining pieces, mark the center edges with an air soluble pen.

Take the two top gusset pieces and fold one long side in 1/4 inch. Press and glue baste. This will create an open space for the zipper.

Repeat the same construction process as you just did for the exterior, with the top gusset pieces leaving a gap in the middle like this. Use a 5/8 inch seam allowance!

Caution: be careful to sew the main panel with the slip pocket on it in the right direction.

Insert the drop-in lining and clip/pin the top outside ends of the exterior/lining together. Sew as far as you can from end to end. Doing this will help the lining keep its shape.

To attach the lining at the zipper, I would definitely recommend using clips instead of pins. The lining fabric should be positioned just inside the zipper teeth. For this portion, I used the techniques found in this Swoon Patterns tutorial for drop-in lining attachment.

For me, this is always the most difficult part of bag construction. Go slowly and don’t be afraid to really manhandle the bag to get it into the right spot on your sewing machine.

When finished, it should look like this.

All that’s left now is making the strap.

On each short end, I folded in about 1/2 an inch and glue basted.

Lengthwise, fold fabric in half – then fold each side in half again toward the center. Glue baste. (I do love glue basting, it is true…)

Top stitch each side 1/8 inch in from the edges.

Slip each end through a swivel clip and make a fold one inch in. Sew a rectangle to reinforce the clip. You could also use rivets instead.

Attach the strap to the D-rings and you are officially done!

Pop open a bottle of Champagne to celebrate!!! Okay, that last step is certainly optional – but after all that hard work you deserve some fanfare!

I designed the Quilted Cube Case because I like the unique square shape. It would certainly be a great conversation starter when you’re out and about, and I could see it being an adorable overnight bag for a younger girl.