Support material idea

Hi all,
I've been thinking about the concept of support material for various prints, and I've had an idea. It probably isn't a new one, but I can't find any references to it.
Basically what I was wondering was using the normal printing material as the support material, but having a second extruder head to print a different separation material. It doesn't event have to be a melted material! Maybe just gelatin? As long as it makes the support structure break away easily...
Thoughts anyone?

Adrian did this by hand by painting oil on the support structure before the real object starts.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

That would work, but doesn't help with automated builds, or complex support structures. But maybe a "paintbrush extruder" ?

YES, that was his idea when he tried it manually.
Apparently it worked very well...

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

A part that wants to warp may break away from support if the tendency to warp is strong enough. The part needs to stick to the support fairly well, at least while warm.

has anyone tested clay as support material?
[reprap.org] the printing of it seems to work wel
so can you print plastic on top of this?