The mellotron is a fascinating instrument. If you're curious, let paul mccartney tell you about it: http://www.youtube.com/watch?v=TUcfB5Whp4I
I used a vst instrument that replicates the sound and behaviour of the mellotron, which also uses sounds pulled straight from the tapes of one, complete with the glitchy effects when a sound/tape has played to its end.
Obviously this is a quick thing (that took me over a week to do) and I'm not as talented as people who've been fiddling with it for years and even decades, but it's still my pride because I've always wanted to be able to make something that sounded orchestral and any bit realistic. I think I've succeeded for once