A classic hot water bottle cosy knit in stocking stitch and finished with an elastic collar in rib.
Begin at the bottom with a seamless cast on and knit in the round on a long circular needle. One always can slide in the bottle and adjust the shape if necessary.

The latest pdf includes a ‘Make it yours’ section, to help to adjust the pattern towards other yarn/needles/dimensions needed.

The seamless cast on can be a bit fiddly at the beginning…- , as an alternative, just knit in the round on a set of needles and close the bottom seam later on.

happy knitting

old version - here