For mass desoldering I have used a solder fountain. Think a giant solder pot with a pump that pumps the solder up a large tube in the center. Works very well for through hole stuff.

This video on building a DIY desoldering iron says it all right ... Rather than accept defeat, [AnotherMaker] purchased a cheap-o soldering iron and a brass tee fitting for small-bore tubing ...

In addition to the soldering iron and 10 interchangeable tips, it included the hot-air rework gun, a voltmeter for checking electrical circuits, and a desoldering pump for removing liquid solder.