Dual Extruder Printer Support Material?

If there is another post simaler to this then please link me to it, but so far I haven't found any yet.

Dual extruder printers are used to bind 2 colors together in a single print, but there is another use for dual extrution printers in industrial printers, and the use for it is so that one head prints the support material, and the other prints the actual print material. The support used by many industrialized printers is very expensive, and I do not know any programs that would use the second extruder to print the "support material", unlike current software, if you would want to print a support material, it would be the same at the material the actual object is made from, and so its difficult to determine what is support material, and what is the actual object, also its difficult to remove ABS off of ABA (or PLA) in tight wedges.

So the 3 challenges for this project is
1: Finding/Creating a software which which can use the secondary extruder for the support material.
2: Finding a cheap, easy to remove (preferably washable) support material.
3: Creating a extruder for that support material.

I am not good with creating software so I will need some help on challenge 1, but I have some ideas for challenge 2 and 3.
The simplistic type of support material would be sand or a gell. You make a box around the print area, and when you print 2 layers of an object, print 1 layer of sand/gell (so some sand/gell wouldnt fall on top of the actual printed item) and for 40 layers, have 39 layers of sand/gell, etc etc. And when there is a over hang, the print will be off one layer which wont be a problem. But how will you have the extruder place down an accurately and evenly amount of sand/gell across the whole print area?

The most easiest mechanical solution would be just to replace the support material with a strong, relatively heat resistant, material which can be easily washed off/taken off, but also cheap.

Any ideas that will solve the 3 challenges?

PVA

most slicers (Slic3r and Kisslicer for sure) allow you to assign a second extruder to the support only or for infill (say you have some scrap color, assign it to infill where it's not seen)

Your sand/gell idea is ambitious and will be mechanically challenging but not impossible, just improbable.

I think what you want available right now.

Well do you have any better ideas?

no, I think avoiding the gel/sand concept is a good idea.

Open discussions about it are great, and continue by all means.
Often, discussions about one idea will lead to another idea and another, ending with a solution that solves the problem.

I think using PVA or even HIPS is a good support material.

You seem to state the problem that is already solved in my mind.
The better idea is done now.

You can also specify which extruder to use for support in Simplify3D.

How would you prevent sand from being impregnated into the extruded filament? How would the filament bond to the support mixture and not move? We have a hard enough time making it stick to things we want to. Such a mixture works for sintering as after the material has been spread, it is not contacted except by a laser so there isn't a force trying to move and disturb the mixture.

I've got a roll of pva specifically to give this a go, but my printer is very off line right now. I considered hips, but I don't like the idea of my prints smelling of oranges.