Tim and Steve have been working on interesting project at high school class. This is called Digital Audio Workstation. This is practically audio synthesizer based on Arduino Mega. It has everything you might need to play various tunes. Tones can be input visually by taping to LED matrix which is placed under resistive touch screen. 2X16 LCD menu displays current position and allows accessing other settings like save, load tune change waveform.
Audio is played through Maxim7224 8-bit DAC, which comes with output amplifier. They had to solve many difficulties during process. First of all to make touchpad interpret correct coordintes so LED matrix would match correct inputs. Also they made 768×24 virtual matrix that can be scrolled inside 8×8 LED matrix. So there were no way to put everything in to large array since audio part also took his part. They made smaller matrix which was updated from full matrix on play to preserve RAM. Anyway in 9 moths they made it working and even play Fur Elise.