Hi Brian
You get the ability to automatically switch between 4 materials.
Righty. That's clearer. That's not particularly complex, depending on how it's implemented. Most printers do it by having multiple extruders, while a few do something funky in the filament feed. I think that using multiple extruders, in general, makes more sense because different filament colours have a different melting point, which means that the extruder temperature needs to be different also. If you use a single head, that becomes finicky to control with quality output straight off. Just in terms of design and layout, you will find that if you have more extruders, your effective build-area is smaller. The heads are on the same XYZ Cartesian bot, so a wider set of heads means you have less X space, a deeper set means you have less Y space. The Wombot Drafter has only one extruder, in part because of this. Most of its bigger siblings have 2 heads. You can replace filament in an unused head without too much fuss while the printer is running (as long as you keep the head warm enough), so having more than 2 heads can be somewhat indulgent. Of course it's a convenience. Mind that filament attracts moisture from the air and degrades. The more filament you have "in use", the more you will notice that in print quality over time. Unless you print an awful lot, I don't think it's a winner to have say 4 spools open in the room. The standard Arduino MEGA + RAMPS 1.4 controller setup, or its equivalent with an integrated controller (I forget the name) has support for 2 extruders, which is also what most software knows about. Of course you can have more extruders, but you'll need different hardware which is not as common, and I'm not certain about the software support. You may be more restricted in what you can use. Open Source 3D printers are adaptable, you can improve and enhance them over time. The key is that you learn about how they work, and how to optimally use and maintain them. It's very important to see a 3D printer as a workshop tool (like a lathe) and not in the realm of "inkjet printer, laser printer, 3d printer". Regards, Arjen.