I will chime in. I have real 3d printers and a poloroid 3d pen. (The one from Kickstarter) The real 3d printers can do so much more than the pen, the pen will never ever do dimensionally accurate prints for example. The real 3d printers also require an ability to model your own designs (debatable sure) and an understanding of slicing software, material settings, and best practices for actually getting good results on the printer. Now, a pen is a lot more beginner friendly. The only steadfast rule is; don't touch the hot parts! They are really only capable of printing PLA , the are a coupe that claim to be able to use abs but let me tell you why that's bullshit. Abs when melted smells like burning rubber. It is actually emmitting a lot of harmful gases and particles. Like a lot. Nobody should be using abs plastic for anything these days, it's one of the most toxic plastics available. And when using a pen your face is right above whatever piece your making. It doesn't even matter that the 3d pens can't actually reach necessary temperatures to thoroughly and evenly heat the plastic while it passes through the melt zone (there isn't one on the market yet that can get hot enough for this). Because your going to stink yourself out of the room before you realize the crap isn't sticking together. On this note it also does not get hot enough to use it to weld other prints together either, not on its own. Add a heat gun to the mix and pre heat everything and it will weld things together So now, back to using PLA in a 3d pen. Give er! You can eat PLA (don't though) the smell is almost sickly sweet and there's so little fume released that it isn't worth taking about further. You can make organic shapes really quickly!

These prints you make with a pen will not be strong. They will not be dimensionally accurate, so two things that fit together is a real challenge. They will not be smooth or pretty. It's best used to make things like fur.