12v to 220v inverter

hey i'm trying to build a 12v to 220v inverter i found a lot of schematics on the internet but i need a circuit to use it with 2 to 3 guitar amplifiers 0.25A each for the longest possible period of time i'm not very advanced in electronics but i have enough experience to be able to build it with some help and schematics.

This is asked all the time here, just buy one - they cost a fraction of what it would cost you to build one, and it will be more efficient, smaller, and lighter.