Highland dress!

Take one jacket, one kilt and one kilt extension piece:

Then join the extension to the back of the kilt with glue or Sellotape with about an inch overlap (need the extension as the kilt made from an A4 sheet of card isn't quite long enough to go around the 2ltr bottle):

Attach the kilt to the bottom of the jacket (glue or tape) with about a half inch overlap, making sure that the jacket is centered over the main patterned part of the kilt:

Join the jacket top around the bottle using the cut slits:

Fasten the back of the kilt closed tightly around the bottle, and there you go: