To 3D Print Something:
You need a 3D print file (often an .stl file). Create your model with modeling software and export as .stl file (or get the .stl from from elsewhere).
Import the .stl file into the manufacturer's software and "slice"; output/upload the
Prepare the printer and do the print.
STL (SteroLithography) is a CAD (computer aided design) file format in which the surface of a 3D object is represented by groups of adjacent triangles. (See Tesselation.) This, and other types of files representing 3D objects, can be produced with CAD modeling software. The first step in a 3D printing project is to create an stl file of the object you wish to print.
A few example CAD modeling programs include:
OpenSCAD (free and opensource): openscad.org
Autodesk Fusion 360 (free for academic): www.autodesk.com/products/fusion-360/
Sketchup (yearly license): www.sketchup.com
Rhino: www.rhino3d.com
VR based:
Scupltr VR: https://www.sculptrvr.com
Shapelabs VR: https://shapelabvr.com
Gravity Sketch: www.gravitysketch.com
These run the gamut from being very algorithmic, code-based programs good for making precise objects that can easily be tweaked (e.g. OpenSCAD) to more free-form virtual modeling type programs (e.g. Rhino, VR based)
STL files can also be found online, for example at www.thingiverse.com . Often research papers describing 3D printed objects will include STL or other print files as supplementary material.
Slicing Basics
Once you have the 3D print file (e.g. the .stl file), the model needs to be "sliced" into directions for the 3D printer. Each manufacturer has their own slicing software:
Formlabs slicer: PreForm: formlabs.com/software/#preform
Raise3D slicer: Ideamaker: www.ideamaker.io
Makerbot slicer: Makerbot Print: www.makerbot.com/3d-printers/apps/makerbot-print/
Download the software and use it to turn your .stl file into a file specific for the 3D printer you plan to use.
Slicing Tips
Each slicer had a learning curve and some subtelties. Correctly orienting your object in the printer is somewhat of an art. Considerations include:
Minimizing supports - the object orientation can have a large effect on the number of supports. More supports are more difficult to deal with in post-print processing, and reduce the quality of the surface finish.
Layer height - smaller can give better resolution but takes longer. A good starting point is ~ 100µm for SLA and 200 µm for FFF.
Rafts - also good to minimize, for ease of object removal. For FFF a raft is often not required. For SLA, a raft is recommended; mini rafts can reduce material usage, and are easier to remove post-print.
Orientation - can affect the smoothness of the finish for both FFF and SLA.
Prepare the printer. To set up the print you need to decide on the filament (FFF) or resin (SLA) you wish to use. Set up the printer with that material, and print.
See specific printer pages for detailed info.