Record you first part. Setup another track
and record another layer or part with the same
patch on the same synth. Layering is such a
simple but often forgotten technique that doesn't
just apply to layering different synths. You
can layer the same synth as many times as
your heart desires (and your DAW track count
allows) :)
Ahh.... Memories. The 1970s, my first synth (multimoog) and a 4-track reel-to-reel tape deck.
I actually did some of this on my first solo CD, playing the minimoog several times by hand.
It really works. Just ask W. Carlos.