Hans has a good how to on making a $45 hot air pencil for desoldering “Many types of surface mount capacitors will delaminate when soldered with a regular soldering iron, the main problem being the thermal shock and uneven distribution of heat across the component. Using a Hot Air Pencil solves this problem, by carefully raising the temperature of a component these thermal shocks can be avoided. So, I needed at least a simple Hot Air Pencil. Checking my favorite catalogs I found several, but the cheapest being $600! Need being the mother of inventions, and refusing to pay the price, I started looking for a way to make my own Hot Air Pencil.” Link.