Mellotron (DIY how)?

[cl]

OK.. I grew up in the 60's (and love Moody Blues)... but I've never needed a Mellotron patch till now. Ive been told "Double patchs and slightly detune..." (I'm assuming detune one anyway)... Anyone have a bit more on this? I'd like to have something that "resembles" the mellotron that I can build out of the standard G patch's & tweak.... but, I don't really know where to start. Thanks