Cura 3.6 has been set up on the 3d Printing Desktop with the recommended profiles. DO NOT overwrite the default profiles - you can create one with a new name to save personal modifications for infill, layer thickness, support, etc.  Note: If you want to install Cura 3.6 on your own machine and set up the Prusa-provided profiles, follow these instructions after Cura 3.6 is installed: Q: How does a STL get turned into a file i can print A: CAM - Slic3r PE the easiest way to get started.  A: CAM - Cura is also an option, but you need to install profiles and configure (see the profiles at the end of this page). The Prusa i3 Mk3 requires the use of either Slic3r PE or Cura to "Slice" [a type of CAM]  from an STL file to a Gcode file. There are setting to control the material properties and aid building the "thing": Layer Thickness: The finer the quality the smoother the surface, and finer the detail. 3X finer takes at least 3X longer to build and slice. Raft - this is a big plate of loose material attached to the build plate that will support tall objects.  Supports - Supports can be generated by the slicer or you can add them to your model where needed. Use Support anywhere "undercut" or "overhang" will not bridge to another supported point. In fill - The interior of most things will be a web of supporting connections to the skin and air.  Skins -  This controls how thick the outside layers are: 2 or 3 is general good. more skins will stiffen fine details while not increasing build times much. Adjusting Speed and Temperature are advanced setting that you should consult an with an RM Temperature - 220C - 240C works best for most things. To hot creates "sag"; to cold cause lack of layer adhesion. Speed - This is a advanced setting that interacts with temperature. Slower can make "smoother" surfaces on curvey objects. In most cases Required selections will make the difference between a build sucess and a build failure. Optimizing most of the settings will take a print from "ok" to "nice".  Selection  Action  Advantages or  Better selection  Disadvantages or poor selection ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------  Layer Thickness  Required  Med - faster, High - finer detail  Med - low Detail, High - 3x more time   Raft  Required  Supports tall objects, fixes large flats  leaves a rough bottom, post work  Support  Required  Required for objects with overhang  leaves a rough under hang, post work  In fill  Required  Less is faster, lighter, and more flexible      More takes more build time , Less is fragile  Skins  Optimize  More detail, stiffer structure                  Takes more build time, Less is fragile  Temperature  Optimize  Hot - better layer adhesion  too Hot = sag, too cold causes structure weakness  Speed  Optimize  slower can use lower temperatures  Takes more Build time, artifacts Designs can be optimized for FDM and here are some videos on how to do that: Maker Faire 2013 Youtube talks