Heh...the idea of using a gel as support is great, though it limits the density of the printed structure (if you print too dense a part it will sink through the gel while you're still printing other parts)

Maybe a way around this would be to use ice as the supporting structure (where the entire injection needle is heated and moves through the ice that way - with the water refreezing behind the needle). While this would decrese printing speed significantly it would allow for more compact objects.

"use ice as the supporting structure"

The material has to flow out of the way, which ice doesn't.

If creating a part of a design that is heavier than the gel can normally hold, just add as small a support rod as necessary to the bottom of the tank to take the weight and which can be trimmed off later. Of cours, that's assuming that suitably denser gels can't be used in the first place when required.

Apparently the gel is non-newtonian fluid, which is why the object doesnt sink or float up in it despite differences in density - it's not pushing hard enough to cause shear thinning, so it stays stuck like pieces of fruit in jelly.

Much like ketchup - stiff when still, flows when you tap the bottle.