It is a tool for desoldering (multi leg) electronic components with 3 or more pins.
Theory behind this project is fairly simple. Dissolved solder in heated container heats all contacts of electronic component placed together with PCB on this tool. All you have to do is remove component from PCB with pliers or with tweezers. So with this device you can easily desolder 25 pin LPT conector from 2 sided PCB.
Original article on my site here