You will need:
Different Yarn colours or your choice (I used 6)
3.5mm crochet hook (or whatever works with the yarn you have)
Darning Needle
Hot water bottle

Notes
Stitches are writing with American stitch names.
This particular pattern is crocheted all in one piece.
Please be aware that the sizes of hot water bottle may vary and therefore the pattern may need adjusting slightly to fit your needs.
I decided to do make sure my total stitches on a full round was a multiple of 6 so it would work well with stitches of 3 & 2.
Remember to check that the cover fits the bottle regularly, especially when stitching the neck.