Just wanted to share some important information concerning the quality of PLA you might use to 3D print.
Basically, the filament you put in your printer can be compared to the fuel you put in your car. It is highly important to use a minimum of quality!
I will only talk about two points here, the filament storage & filament roundness.
Filament storage is highly important when it comes to protecting your plastic from moisture. In fact, regardless of the quality, plastic will absorb moisture and create small water bubbles in the filament itself. The problem with these small bubbles is that when heated at the tip of your extruder, they will reach boiling point (~100 Celsius) and explode. This will dramatically reduce the quality of your prints. With all the information above, you should now be looking for individually wrapped spool with desiccant.
Filament Roundness is another extremely important point. Even though when you extrude, your filament is deformed by the extruder wheel, having a inconsistent diameter prior to the extrusion may lead into extruder failure. This is because your extruder wheel can lose grip over the filament.
For more information on PLA and on how to evaluate the quality of it, check our article: http://bootsindustries.com/portfolio-item/importance-of-good-filament/