If you know anything about personal 3D printing, you know one of the primary barriers to entry is hardware ease-of-use. 3D printer manufacturers address (or don't address) the issue with proprietary hardware or software, or both.  Open source is great for a lot of things, but let's be honest.  There are reasons HP and Epson 2D printers don't come with instructions for downloading generic open source software and drivers from GitHub or SourceForge.  The axiom, "jack of all trades, master of none," comes to mind.  In order to easily take advantage of features unique to a single hardware solution, one must write software specifically for that hardware solution.  This is why companies like PP3DP (UP!), MakerBot and 3D Systems provide proprietary software for their 3D printers.  It isn't to force you to use their printer.  It is to improve your customer experience by making their printer easier to use.

Fair warning to sensitive readers:  We are about to delve into a particular ease-of-use vulgarity not commonly covered in 3D printing media, but all too commonly recognized by 3D printer consumers as an immense source of frustration and loathing – build platform leveling.  Without getting into all the mechanical details concerning the way personal 3D printers work, it is necessary to explain the importance of a level build platform. 

Most personal 3D printers melt plastic in thin layers through an extrusion nozzle onto a build surface.  This is known as Fused Filament Fabrication (FFF).  These layers can be two tenths of a millimeter thick or less.  To give you an idea of how small two tenths of a millimeter is, it is about the same height as a piece of paper folded over onto itself once.  As the first layer of melted plastic comes out of the extruder, it needs to be roughly the same distance from the build platform as the layers it is producing are thick.

In other words, if you are going to print an object with a vertical resolution of two tenths of a millimeter (200 microns), your build surface needs to be two tenths of a millimeter underneath the extrusion nozzle when the first layer is extruded.  This distance must be consistent across the entire build platform.  A slight warp, nick, or tilt in the platform could mean a low quality print job or complete failure.  A more significant platform leveling issue could make the nozzle contact the build surface during printing, the 3D printer equivalent of a hard disk head crash.

Suffice to say, trying to eyeball a 200 micron gap isn't likely to achieve the desired result.  You're going to either need an engineer's measurement tool capable of being used in a very tight space, or the 3D printer manufacturer must provide some kind of method to help you know if your platform is level and at the proper distance from the extrusion nozzle.