Howdy! If you're like me, you've got a stash of reusable shopping bags collected from well-meaning retailers. They pile up, don't they? Well, let's up-cycle some of them into something a little more hands-free: a utility backpack.
I tried to use old bags exclusively for this project, and minimized new materials. You will need basic sewing skills and the following:
Fabric measuring tape
A number of non-woven polypropylene shopping bags. Try to choose colours that will go well together.
Foam padding or liner to cushion the back
Thread. Probably black, but you can use anything you like.
For the straps: about 2 yards of 1.5" webbing and 4 1.5" D-rings (you can use something else for straps if you prefer)
Optional: large buttons, or other hardware to close the flap.
Step 1: Gather Materials and Prepare the Basic Structure
Non-woven polypropylene fabric is made from old pop bottles and other recyclables. There are two types: coated and uncoated. The coated kind is a bit glossy and smooth to touch. It's better for the outer shell and flap of your bag, in case of rain, but it's stiffer, harder to work with, and tougher on your sewing needles. The uncoated is better for the lining and everything else.
First, select a bag for the main outer shell of the backpack. Find something that seems durable and whose width can accommodate what you might carry (i.e. your laptop or books). Decide which side will be the front and back. Trim off the carrying straps. (If you think you'll want a handle on the finished product, you could leave one strap on the back side. Cut the this bag exactly as shown.
Second, select a bag for the upper panel and front flap. Cut off the extra parts (see photos) and fold the faces together. You can add an additional layer(s) of fabric on top, at the bottom of the flap, for extra weight and strength. Stitch 3/4 of the way around, leaving an opening on the top.
Turn the flap right-side-out. This is a good time to add decorative stitching, patches, or other extras, to the flap.
Step 2: Prepare the Lining
Select uncoated bag or two of a colour(s) you'd like for the inside lining of the bag.
Cut three panels to size, matching the front panel, bottom, and back panel, plus a generous seam allowance.
For my bag, I used a yellow lining for the front and bag, and doubled up the bottom with green. Stitch them all together front-to-front, then flip it back over.
While you're at this step, get some thin foam for padding the bag panel (and the bottom, if desired), and cut it to match those two panels. Later when we assemble the bag, we'll sandwich this between the liner and the bag.
Step 3: Now Add Straps or Do What I Did...
I didn't have a plan for the straps when I made this bag. If I'd planned ahead more, I would have bought webbing first, then sewn it directly into the bag. Ah, hindsight. Anyways, here's what I did. You can iterate as desired.
Find those handles you cut off earlier and fold them in half. Sew around the edges and then corner to corner. Find a good placement on the bag, along the top of the back panel. Sew them securely on to the bag.
Using more handle straps, make two more loops and sew them onto the bottom of the back panel.
The important thing here is to get your straps attached before assembling the bag.
Step 4: Putting the Bag Back Together
Now it's time to turn this into a 3D object!
Connect lining. Lay out the bag pattern and orient it with the top flap piece. Lay the foam on top over the back panel and bottom, then the lining on top. Stitch together all the way around the lining.
Attach flap. With the back panel and flap piece face-to-face (and the straps in between), sew down the edge, closing the flap.
Last call for pockets or other modifications. I added a few side pockets on the side panels using some leftover pieces.
Sewing the bag back together. This is a little challenging but it's not that bad if you take your time. Refer to my photos and Paint illustration. Once you're done, flip it right side out.
Now, you had done proper straps already, you'd be nearly done. Moving on...
Step 5: Fixing the Straps and Adding Extras
Since I just had strap connections sewn in, I needed an extra step to connect some 1.5" webbing. I bought 2 yards worth - 1 for each strap. I added two D-rings per bottom strap, and almost a yard worth of strap to the top, closing off the ends to prevent fraying.
Keeping the flap closed
You could use parachute buckles or something else fancy to keep the flap closed, but I wanted something cheap and recycled, so I grabbed a couple of giant buttons that I'd saved, and made buttonholes on the flap. I then marked the spot and sewed the buttons to the bag.
Add any additional stitching you want and customize it further. For example, maybe you could add padding to the straps or extra d-rings to hang stuff from?