unless you build sideways (which there’s nothing really absolutely against) the hard limit for a 3D printing arrangement will be the height between the bottom of the case and the gantry.
Which is about 4" as far as I can tell.
Hmm. Can anyone else make a compelling argument against sideways?
Sideways? You mean like Speculation on the Expansion Port? (sorry to link again if you already saw that)
I missed that. No, I mean really sideways. Something like this
In theory if you have good cooling or use certain filaments you won’t sag. Some of the overhang rules and the within-layer sequencing will be different. But I don’t think it’s completely insane per se.
I am thinking about calling mine, “The Great White Whale.”
Elusive and you want to murder it? Those feelings will pass. 
Ha, the unobtainable, mythical beast.
Good point, I hadn’t thought of that. Of course, you could add some fasteners to the router head to hold it on tighter. But then again, if you’re going to do that, why not just use fasteners from the beginning? Seems like it’s going to be most suited to low-load applications… unless they beef it up with mounting strategies that could have been used from the beginning.
I thought about sideways but had no idea if it was actually feasible. Would the new layers hang on without a base? I suppose not a lot different than something with a small base that expands out and overhangs? How does that work on most 3D printers?
Gravity?
Don’t give @dan any ideas - or he’ll delay the next shipment date because the GF can’t cancel gravity yet…
Usually filament sticks to the base of to the layer below because it’s molten plastic being squished against something that it’s compatible with. And with nonstandard tools like the 3Doodler, there’s no a priori problem with attaching stuff from the side (I’ve done it with some amount of success). Usually that adhesion is helped by the fact that each layer of plastic takes a while to cool down, and sorta lets the next layer melt into into – but that means the plastic can be soft and sag. (It depends on the plastic – some stiffen just below melting, others stay soft at ridiculously low temp).
Meanwhile, though, I realized that all of us have been imagining (more or less) a standard gf configuration for these addons. For some of those that will be true, but for others, since it’s not a laser any more it won’t need to operate with the lid and the front door closed. So a 3D printer might have much more vertical space available to it (if you could get around the issue of having to fit the prints under the gantry, which you might with a big offset assembly and some counterbalancing (read up on Bowden extruders…).
Also, because the current head is not light, and the Y-axis is designed to move the tube around, I think the x-y drive mechanism probably has a long more force available to it than we would usually think.
