I don't know about you but our car always seems to be cluttered with rubbish. It seemed sensible to make something fun and useful that would harness it all.
Two squares outer fabric 28cm wide by 29cm high. Same in lining (I'm using shower proof fabric) Cut a piece 10cm by 35cm for the strap.
A strap made the easy way - fold in half lengthways, press a crease at the half way point all the way down the length, open out, then bring the 2 long raw edges to the initial crease and press 2 new folds (these will be a quarter of the way from each long edge,) then fold the long folded edges back together. (the strap will now be a quarter of it's original width) All the longer raw edges will now be enclosed. It also needs the raw edges hiding by folding them in at one end as they'll not be enclosed in a seam. They'll have velcro on.
Leave a 2cm gap on the lining seam, 2.5cm down from the top edge on one side only.
Leave a gap for turning, along the bottom edge of the lining.
Use 4 small pieces of Wundaweb to keep the seam allowances glued down either side of the small gap in the side seam and in the same place on the opposite seam. Repeat in the same places on the outer fabric side seams. This will keep the casing open for feeding through the corset boning/parcel strapping.
Stitch side and bottom seams on outer fabric. No gaps this time.
Press seams open and trim corners.
Find half way along one of the top edges of outer fabric (I've notched it) and 'machine tack' the end of the strap in place (the unfinished, raw end).
Create 'T junction' corners. 8cm across on all four corners. (2 on outer fabric, 2 on the lining)
Matching up the seams, drop one bag inside the other right sides (RS) together. Stitch all the way around the top. 1.5cm seam.
Trim seam allowances if necessary. Then, turn right side out and close the gap in the lining by machine edge stitching it.
Top stitch twice around the top of the bin. Once above and once below the gap. This will form the casing through which you'll push either parcel strapping or corset boning. (This will keep the top open - much easier than faffing about when you're driving).
Feed the strap by trimming a curve. Feed around the casing until the ends of the strap meet. Then cut. You'll be able to stitch through the strap with a zigzag stitch to close the gap.
This is the wide zig zag - very small stitch length - to close the gap.
Lastly, take the bin to your car, with two strips of velcro (one hook and one loop side) and explore where you'd like to hang it. Wonderclip/pin the velcro strips in the correct place until you return to your machine and stitch them in place.
Ta dah! Your bag is finished.