The chip in my home brew is mounted on stripboard, the chip is the same one used in most Deumilanove/Uno/numerous clones. The Leonardoi is surface mount and wouldn't fit, Surface mount is tricky on a small scale hobbyist level. At a push you can program the chip on a Uno, lever it out of the socket and stick in it your own board. Its just about practicalities.....
The other picture shows it mounted on what I designed it for : mounting on a Raspberry Pi. Raspberry Pi Documentation