When someone is trying to put the finishing touches on their drywall installation, they should have a variety of drywall finishing tools around.  Everyone should have putty knives available to them at all times.  These knives come in all different sizes to meet your different needs.  It is a good idea to have knives all the way from one to six inches.  This allows for many different options as you will find one size knife works better in certain situations.  The bigger knives are great for spreading out the compound, and the smaller knives can put on the finishing touches.  Putty knives are a must have when it comes to buying drywall finishing tools.