First find a wool blazer (I got mine in the second-hand store), then shrink it in a really hot wash to felt the fibres. Then cut both sleeves off and put one inside the other (right side out). Pull the wrist end of each sleeve together and stitch firmly to form a base, then over-sew one top edge over the other top edge to hide the raw edges and create the top of bottle cover. I slipped elastic into the top seam and tightened it a bit: enough to stop the cover slipping off the bottle in darling daughter's school bag but not enough to prevent the bottle being removed for washing. Then I embroidered her name on it.
