Library for Atmels AVR Microcontrollers

Hey my most recent project with arduino is putting together an LED matrix to display time, temperature, and a few other messages. The only problem however, is that board space is limited and I don't want to fix a 30+ dollar micro controller to the projects when I only need fifteen I/O's. I've seen tutorials on youtube for programming the ATTiny 85 but otherwise not to many to do with any other Atmels AVR. So I was wondering how I would go about programming another Atmel chip with the Arduino as ISP library? Help would be greatly appreciated. (I'm new to the forum, so please excuse me if this sounds stupid and I'm missing the obvious)

Same instructions as for the ATtiny85. Download and install a core. Upload ArduinoISP to your Arduino. Disable auto-reset. Disconnect power. Connect MISO to MISO, MOSI to MOSI, SCK to SCK, pin 10 on the Arduino to RESET on the target. Connect the Arduino to your computer. Select the correct board. Program.

I appreciate it!