This is one of my favourites; the “Fässing” (in Swedish), Martebo-sack (from Martebo church on Gotland) or a Wallet (18-19th century). It is a simple, practical linen bag made for carrying loads. I have seen medieval examples worn over your shoulder like below or larger ones strapped over a donkey.
I actually have several of these for my medieval adventures; for grocery shopping, for the picnic, for my showering things like schampoo…
The bag is made with a piece of sturdy linen or hemp canvas (chose a sturdy tight-woven fabric in linen, or a piece of tent fabric for a large sack).
Cut out a rectangle with the measure 140 * 70 cm, to make a bag suitable for a picnic and your warm hood. Or design your own measures by laying a measuring tape over your shoulder and let it hang down on either side. Adjust and decide on a length you like on the bag, and then decide on the width; between 60-100 cm (makes a bag that is 30-50 cm wide) might be nice. Add 3 cm of SA (seam allowance) to each measure.
1. Mark out the opening on the long sides on the rectangle. It should be in the middle, and between 30-40 cm wide.
2. Put the long sides on top of each other, and sew a seam on either side of the opening. Backstitches with waxed linen thread (if you are using the sewing machine, start with zigzagging the whole fabric piece, then sewing this seam).
3. Press and fold down the SA and whip stitch it down to one side for extra strenght.
4. Hem the opening with whipstitches, working from the inside. It is also good to reinforce the edges of the opening by sewing a couple of extra stitches through each fabric piece to make it less prone to rip open.
5. Now you have a tube, adjust it so the seam is in the middle of the fabric piece inside out, and pin the short edges closed.
6. Sew the edges with backstitching, and repeat the pressing and folded down SA. Done!
The sack may be carried over your shoulder, or wrap it around your wrist and hand to carry it like a grocery bag. If you have valuables in it, you can also make a knot in the middle over the opening to prevent anything from falling out. Very convenient!