Ah, I was working on a similar idea when I was in upper secondary school. But I was unable to do get what I want with my very limited electronics knowledge back then :)

I was thinking of storing and playing the data in an analog way, pretty much like a regular compact cassette meant for audio. I thought it was a better idea after seeing audio casettes can store 60/90 minutes of audio but they can hold only very little digital data (I had a commodore that I found in my grandma's cellar and those casettes were my unit of measure)