Knitting Needles Roll
=====================

This is a fabric roll to store knitting needles, designed to fit
precisely needles of known sizes.

Materials
---------

Fabric
^^^^^^

* Scraps or ~25 cm sturdy printed cotton for the outer layer.
* Scraps or ~25 cm stable but soft cotton for the lining.

Notions
^^^^^^^

* Bias tape, 1.5 cm wide when folded: 
* Ribbon
* Sewing thread


Pattern
-------

The pattern is made of simple rectangles; to make a roll that precisely
fit a set of DPN you can use the following python code: enter the sizes
in mm of the needles you want to fit as a tuple, e.g.::

   > sizes = (
       2.00, 2.25, 2.50, 2.75,
       3.00, 3.25, 3.50, 3.75,
       4.00, 4.50, 5.00, 5.50,
       6.00, 6.50, 7.00, 8.00
   )

and then calculate the sizes of the slots and the width of the finished
roll::

   > [math.ceil(s * 5 / 5) * 5 for s in sizes]

   [10, 15, 15, 15, 15, 20, 20, 20, 20, 25, 25, 30, 30, 35, 35, 40]

   > sum([math.ceil(s * 5 / 5) * 5 for s in sizes]) + 30

   400

And the height of the roll should be the height of the needles, plus 4
cm (e.g. for 20 cm needles it will be 24 cm).

The part of lining that holds the needles will have to be wider:
calculate the slots and total width with the following python code::

   > [math.ceil(s * 7 / 5) * 5 for s in sizes]

   [15, 20, 20, 20, 25, 25, 25, 30, 30, 35, 35, 40, 45, 50, 50, 60]

   > sum([math.ceil(s * 7 / 5) * 5 for s in sizes]) + 30

   555

its height, finished, should be 3/4 of the height of the full roll (in
our example 18 cm).

Finally, the finished top flap should be 3 cm less than the width of the
full roll, with 1 cm sewing allowance on the sides, and 1/3 of the
height of the full roll, in our example 37 cm × 8 cm.

Cut the following pieces:

* base: cut 1 in fabric and 1 in lining, as wide and as tall as the
  base, calculated above (e.g. 40 cm × 24 cm); 
* needle holder: cut 1 in lining, as wide as calculated above and twice
  as tall (e.g. 55.5 cm × 36 cm);
* top flap: cut 1 in lining, as wide as calculated above plus 1 cm
  sewing allowance *per side* and twice as tall (e.g. 39 cm × 16 cm.

Instructions
------------

Fold the needle holder in half, wrong sides facing, press.

Mark with chalk or a vanishing pen the channels measured above on the
lining base and on the needle holder; 

Place the lining base with the right side on top, and carefully align
the needle holder over it such that its long raw edge (opposite to the
fold) is aligned to the base, and the center seam matches. Pin in place
and sew the center seam.

Moving towards the sides, align each seam between the base and the
needle holder, pin, sew, and then work on the next seam. At the end the
short sides of the needle holder should match the short sides of the
base.

Make a box pleat at the bottom of each channel, pin them and sew along
the long raw edge, about 1 cm from it.

Prepare the top flap: turn it with right sides facing and sew the short
sides with 1 cm allowance. Clip the corners, turn inside out and press.

Attach a piece of ribbon to the fabric base, close (about 3 cm) to the
center of one of the short edges, and any label or embellishment you
want to add to the top.

Place the base fabric and base lining + needle holder wrong sides
together, sew along the sides and bottom edge, about 1 cm from it, being
careful not to sew the ribbon. Place the top flap centered on the top
side of the lining, and sew also the top edge 1 cm from it.

Turn the roll with the fabric side on top; starting from the short edge
with the ribbon sew the bias tape all around the edges, taking care to
miter the corners.

Turn the bias tape towards the inside, whipstitch it in place by hand.

Variants
--------

Flat needle slots
^^^^^^^^^^^^^^^^^

Instead of making box pleats at the bottom of the needle rolls you can
make the base and needle holder the same size, and sew the bottom flat.

In this case, the python code to calculate the width of the slots
becomes::

   > sizes = (
         2.00, 2.25, 2.50, 2.75,
         3.00, 3.25, 3.50, 3.75,
         4.00, 4.50, 5.00
     )

   > [math.ceil(s * 6 / 5) * 5 for s in sizes]

   [15, 15, 15, 20, 20, 20, 25, 25, 25, 30, 30]

   > sum([math.ceil(s * 6 / 5) * 5 for s in sizes]) + 30

   270

and in this example for a set of 13 cm DPNs the fabric to cut would be:

* base: cut 1 in fabric and 1 in lining, 27 cm × 17 cm;
* needle holder: cut 1 in lining, 27 cm × 26 cm;
* flap: cut 1 in lining, 24 * 12.

When assembling, you can then mark the channels just on the needle
holder, pin it in place aligned to the base at the bottom and short
sides, and sew all the channels at the same time.

Everything else remains the same.