Was it possible in the 60's to make your own samples for the mellotron?
But that means that the flute sound at intro of strawberry fields is not an unique sounds because there were many mellotrons made with that flute sample?
No, and indeed it still isn't - a Mellotron is an analogue synth!
More of a tape playback device.
I think I know everything I wanted to know about the mellotron now!