1. To make the template, lay the hot water bottle on a sheet of A3 paper and draw around it, remove the
hot water bottle and draw a 1in (2.5cm) border around the outline, simplify the shape around the top of the bottle keeping the border at a minimum of 1in (2.5cm). Cut out the template and put to one side.
2. Using the Clamshell, 4 1/2in Unfinished die cut approximately 24 clamshells from thick paper or card. Arrange the templates together in rows as in the finished design to check that there are enough to completely cover the hwb (hot water bottle) cover template with 6 left over for the reverse opening edge. Cut more if required.
3. Fix a paper template to the reverse of your fabric using a pin or some basting glue and cut out a clamshell from the fabric leaving a 1/4in (6mm) border around the edge. Cut 3 clamshells from the fabric that will be used for the back of the hwb cover (these will be on the inside of the shells that edge the opening).
4.To prepare the clamshells I used the following technique using kitchen foil that I saw featured in a pattern by Jo Avery in Love Patchwork and Quilting. Firstly spray the fabric with a little starch and place it with the paper still on the reverse, on a piece of kitchen foil (1). Pull the foil inward following the curve of the template and smooth down (2). Next, press the curve flat with an iron (3). Lastly remove the foil, press the clamshell again with the iron and remove the paper template (4).
5. The next stage is to pin and then sew the clamshells to some lining fabric, row by row just around the top curve. To fit my cover, I needed one shell on the top row.
Two on the second and then three on the third. From then on the rows alternated between two and three clamshells per row. For an even finished look it's important to keep the rows straight and in line both horizontally and vertically, so it's helpful to use a ruler to position the shells for pinning. Folding the shells over and finger-pressing them to find the centre also helps with lining them up.
Eight rows were enough to fit my hot water bottle cover template.
6. Once the clamshells are sewn in place and cover a large enough area to accommodate the hot water bottle cover template, mark and cut out the front piece.
7. Make a quilt sandwich with the front piece, some batting and lining fabric to back it, quilt however you choose (I quilted around the outer edge of each curve).
8. To make the lower back section to the hot water bottle cover, measure approximately 4in (10cm) down from the 'shoulder' of the hwb cover template and make a horizontal fold across the template at this point. With the top folded over, use the template to mark out the bottom back piece of the cover leaving a 1/2in (1cm) border of fabric after the fold in the template.
Mark out the upper back section of the hwb cover in the same way as for the lower but this time using the top section of the template and once again leaving a 1/2in (1cm) extra bit of fabric after the fold in the template.
9. With the 6 leftover clamshells (three in the same fabric as the back of the hwb cover and three in printed fabric) right sides together whipstitch a printed front to a backing fabric shell around the curve. Repeat twice more for the remaining 'opening edge' shells and then remove the paper templates, turn them the right way and press with an iron.
10. Slice off the bottom of the 'opening edge' shells being careful not to cut through the hand-stitching. Right sides together, pin the central clamshell in what will be the centre of the opening and then pin each of the side ones in place, overlapping the central one slightly. Baste them in place.
12. With right sides together, lay this top back piece on top of a piece of lining fabric that is cut slightly larger than it overall and place both on top of a piece of batting. Pin and then sew all 3 layers together along the straight edge.
12. Trim away any batting the overhangs the hem and then fold the upper back piece back so that the batting is in the middle and safety pin the three layers together ready for quilting. Top stitch along the bottom of the upper back piece, the 'opening edge'.
13. Make a quilt sandwich with the lower back piece some batting an a piece of lining fabric and then quilt the upper and lower back pieces as desired (I used a water-erasable pen and a paper clamshell template to mark out the quilting design. Bind the top edge of the lower piece in the same fabric.
15. Sew the front and back together with a small seam allowance so that the stitching won't show after binding. Bind the edges of the hwb cover, easing the biding around the curves and concave/inward corners.