I used an A4paper for measuring. This does not mean the bag is A4sized, it is a bit bigger.
This bag is so simple to make, yet comfortable and spacious.
Step 1: Items Needed
1. Two pieces of fabric 40x150cm. You can pick two really nice ones since the bag is reversible.
2. 2 meters of bias tape 18mm wide
3. A pair of scissors
4. A pencil
5. An iron (not shown in picture)
6. A sewing machine (not shown in picture)
7. Two pins (unless your are a dedicated pin-user, in that case you will need loads) (not shown in picture)
8. Of course, an A4paper (if you like to live on the edge, try lettersize)
Step 2: Measuring
1. Put the A4paper with its short side next to fold. The center of the paper should be in the center of the fabric. Mark corners.
2. Put the A4 paper with its long side next to previous markings. Mark corners.
3. Use the markings made in (1) and make a nice smooth curve from top of fabric (folded side) to first markings. Cut.
note: there will be approximately 5 cm of fabric outside markings. This is ok as this will later on form the sides of the bag.
note #2: In the picture it is hard to tell the A4paper is centered as my piece of fabric is wider than 40cm.
Step 3: Start the Stitching.
Do not stitch on the curved side.
Step 4: Trim Corners and Iron.
The trimming is to be able to do some nice ironing on seam allowances.
Ironing is not the funniest part but makes it look really nice further on.
Step 5: Bring Forth the Old Paper
Step 6: More Stitching.
Step 7: And Again...
Keep the other one turned wrong side out.
Step 8: Finish
Step 9: The Finished Bag
In this picture the bag is filled with a large towel, a book, a swimsuit and a 1,5 l bottle. Still plenty of room.