Zip A Bag Chapter 12: Collapsible Box With Zippered Base

Today, we're going to revisit a couple of old projects to familiarize ourselves with this technique:

I call it the "zippered base technique". When the zipper is open, the base splits apart, allowing a bag/bin/container to collapse flat. 

We first discussed it in this post, in which I made book bins for Emily and her cousin.

I'm going to repost the zippered portion of that tutorial here, for your convenience.

Step 1: Make the double-layered zippered base.

• Find a zipper that's much longer than the diagonal of the base. Ours was a square base, split into two equal triangles. And our zipper was vintage, meaning that it's older than my mother and came from her stash - check out the age stains. 
• Lay the zipper RS up on the RS of half of the BOTTOM layer of the base. This is the layer that the bin will rest on, not the lining layer. Attach one side of the zipper tape to the widest dimension (in this case, the diagonal) as shown.

• Next, lay a lining triangle (the lining will be the top fabric) on top of the zipper-and-bottom-fabric-triangle. Sew this lining triangle to that same edge of the zipper tape, so that you have the zipper sandwiched between two fabric layers.

• Fold both fabric layers over to bring their WS together, and to expose the other edge of the zipper tape, hiding all SA. 

• Press this fold and topstitch (or edge-stitch).

• Repeat the same process to attach the other pair of fabric triangles to the other edge of the zipper. Here is the lining side.

• And here is the bottom side. Baste around all 4 edges, through both layers, to make a composite base. 

We will next make the walls.

These are the two wall layers, each sewn along their short edges into a wide tube. Our outer layer has the embroidered pillowcase hem topstitched onto it. 

Step 2: Make the lining wall. 
Fold the lining wall into four and mark the quarter distances (assuming your bin is also square). Lay the two pieces RS together, and match up the corners of the base to the quarter distance marks (red arrows), 

splitting the SA of the lower edge of the lining wall to allow the corners to lay flat as shown. Sew around the bottom edge of the lining wall to attach it to the base. 

Step 3: Attach the outer wall.
The process of attaching the outer wall is the same as that of attaching the lining wall (Step 2). Flip the base over so that its bottom side is facing up. Tuck the attached lining walls underneath and out of the way. Lay the outer wall on the base as shown, matching up its quarter distances with the corners of the base,

and splitting the SA in the corners as before. 

Sew to attach the outer wall to the base, using the same stitching line as (or a slightly deeper SA than) the one that attached the lining wall to the base.

This will produce sharp corners in both the outer layer

and lining.

Step 4: Join the wall layers.
If you're planning for rigid walls by using inserts (cardboard, plastic, etc.) you will need to partition off the walls into sections. Our box has a square base, so we'll be dividing the wall into 4 equal sides.

Line up the quarter distances (which should correspond to the corner edges of the bin) of the lining and outer wall layers (red dashed line). Pin together, and stitch both layers together along these lines.

This will give four compartments between the walls to insert the cardboard pieces. Do this now. 

Step 5: Bind the opening of the bin. 

I used bias tape, sewn first to the lining side of the bin and folded over to the outer side and hand-stitched. This was the only method permitted by the rigidness of the cardboard. If you're making a softer bin, using only, say, batting for the structure, you might be able to machine-stitch this binding on.

The finished bound opening.

Shot of the inside of the box

and the outside.

In the next post, we'll be using this technique to make a collapsible bag. See you then!