Take a piece of wood (pine) 27cm long, 10cm wide and 2cm thick.

Cut and drill it as shown.

Work out the length x by modelling the bottle as a line. The bottle and wine holder (wood) then make up two sides of the triangle ABC.

To make the holder stable, the centre of mass of the bottle and wood must be over the point of contact of the wood with the table.

So the distance AB must be a little less than half the distance from the neck of the bottle to the base.

For an average wine bottle we estimate the distance AB to be 13cm. Now use the cosine rule to work out the distance x.

If your wine holder tips a little, try stabilising it by either moving the bottle further in or out of the hole, or by shaving a little off the appropriate end of the wood, but do this very gradually.