http://www.torahtots.com/torah/39melachot.htm38. Makeh B'Patish - "The Final Hammer Blow" Striking the final blow (Finishing an object)
This Melacha has its roots in the building of the Kerashim, the beams of the Mishkan. These beams were made of wood covered with gold. The gold sheathing was kept in place with golden nails that were hammered into the wood. The final hit on those nails to complete the beam was Makeh B'Patish. Although the Melacha stemmed from work done with a hammer, the prohibition applies to any act of completion. For example, putting shoelaces into a shoe for the first time may be prohibited on Shabbat because of this Melacha. The Melacha can also apply to liquids: carbonating water, according to some, is also Makeh B'Patish.
It is interesting to note that restoring an item is not considered an act of creation and is therefore allowed on Shabbat. For example, a pendant that fell out of a necklace may be replaced because both the necklace and the pendant were not "broken" in their separated state. The same applies to a shoelace that came out of a shoe. There is also discussion about opening soda bottles. Some argue that by taking the cap of the bottle one is rendering the bottle as usable to store soda in. This may be considered an act of completion. Others argue that the bottle with the cap on it is also a complete functioning vessel, so removing the cap may not be considered creating a new vessel.
There are a number of Rabbinic prohibitions that emerge from this Melacha. One prohibition is that of playing musical instruments. The Rabbis made this prohibition to prevent people from playing and accidentally tuning the instrument. This would be considered Makeh B'Patish.
Singing and whistling are not included in this prohibition. Another prohibition is that of tovelling dishes on Shabbat. Because one is not allowed to use the dishes before immersing them, the immersion gives off the appearance of "repairing" the object.
Makeh B'Patish is a fascinating and broad Melacha. It is extremely complex because it can apply to almost anything. It is one of the few Melachot that are not tied to performing a specific action. It focuses on the result, not the actual action. As such, there is a large volume of Rabbinic literature dedicated to understanding the exact nature of the prohibition. For further research one can look at the sources listed below or any of a multitude of other sources.
http://www.torah.org/learning/tabletalk/5764/hayesarah.htmlDID YOU KNOW THAT
On Shabbat making a noise with any device designed for that purpose is forbidden. The prohibition covers bells, rattles, flutes and whistles. All devices of this nature are muktzeh and may not be moved except in special circumstances as outlined in the laws of muktzeh.
Whistling with one's mouth is permitted. One may give a baby toys that make noise when shaken or squeezed even though such toys are muktzeh but an adult may not make the noise with a rattle or such toy even to amuse the baby.
[Source Shemirath Shabbath K'hilkhetah chapter 16:2,3]