“My hot water bottle cover uses Scheepjes Metropolis, which is a really soft, bouncing yarn in vibrant colours,” says Mary Henderson. “It is knitted in the round and has an envelope opening with buttons for closure. I chose small buttons from Textile Garden - the eyelet buttonhole band means the number of buttons and position can be decided at the end. The yarn is quite stretchy, so it makes for a snug fit, helping your water bottle to retain its heat on a cold night.”