3D printing is also known as desktop fabrication or additive manufacturing, it is a prototyping process whereby a real object is created from a 3D design. The digital 3D-model is saved in STL format and then sent to a 3D printer. The 3D printer then print the design layer by layer and form a real object. 
In 3D printing area, people say “If You Can Draw It, You Can Make It”. So, it is clear that almost anything could be made using a 3D printer. However complicated objects can only be made by professional 3D printers, but they are very costly.
Versatile materials are used for 3D printing, majority of which are plastics, such as ABS plastic, PLA, polyamide (nylon), glass filled polyamide, stereolithography materials (epoxy resins), photopolymers and polycarbonate. Silver, titanium, steel and wax can also be printed using high end machines.
Basically three techniques are there for 3D printing.
SLS (selective laser sintering)
FDM (fused deposition modeling)
SLA (stereolithograhpy)

If you’re just getting started you can try some of 3D modeling software which can be downloaded for free.
Google SketchUp – This Google SketchUp is fun and free, and is known for being easy to use. To build models in SketchUp, you draw edges and faces using a few simple tools that you can learn in a short time. With with Push/Pull tool you can extrude any flat surface into a 3D form. Furthermore, it works together with Google Earth, that you can import a scaled aerial photograph directly from Google Earth, or use SketchUp to build models which can be seen in Google Earth.
3Dtin – The simplest 3D software. You can draw directly from your browser.
Blender – Blender is the free open source 3D content creation suite, available for all major operating systems under the GNU General Public License. Blender was developed as an in-house application by the Dutch animation studio NeoGeo and Not a Number Technologies (NaN). It is a powerful program contains features that are characteristic of high-end 3D software.
OpenSCAD – OpenSCAD is a software for creating solid 3D CAD objects. It is free software and available for Linux/UNIX, MS Windows and Mac OS X. it does not focus on the artistic aspects of 3D modelling but instead on the CAD aspects.
Tinkercad – Tinkercad is a new and faster way of creating designs for your 3D printer. With only three basic tools you can create a wide range of useful things. Once your project is ready simply download the STL file and start your 3D print.

You can also draw 3D models using any more complex 3D modeling software like 3D Studio max, AutoCAD 3D, Maya, Rhinoceros, Solidworks etc.

It depends on the size and complexity of the print, and also on your chosen layer height. A finer, higher resolution print will take much longer, but will look very much smoother.
For doing two things:
Printing with two different colors of plastic. You can get great-looking results with this technique, like this globe.
Have one nozzle printing support material (like PVA) while the other prints PLA or ABS. With this technique, you can print any object, no matter how large the overhangs are. Although slicing software like Slic3r is capable of generating support material that will be printed in ABS or PLA, it requires cleanup at the end of the print. The great thing about PVA is that it’s water soluble, which means you can throw your part into a warm water bath once it’s done to dissolve the support away.
Is PLA more suitable or ABS for printing?
PLA: Biodegradable, corn-based plastic. Prints at ~180 *C, and doesn’t warp, so you can print big things without a heated bed.
PLA will “ooze” more than ABS will — if the nozzle is hot and there’s plastic loaded, it will drip.
For all printers, the nozzle should be about ~0.2mm away from the bed (about the thickness of a sheet of paper).
Because of its low melting temperature, it probably wouldn’t be a good idea to leave a PLA part in your car on a hot summer day, because it will warp!
Available in 1.75mm and 3mm.
ABS: Not biodegradable, but stronger than PLA (same material Lego bricks are made out of). Prints at ~220 *C, and will warp, so a heated bed is needed.
If the user is getting warping problems, either the bed isn’t hot enough, or the Z-axis isn’t calibrated properly.
The bed should be at least 80 *C, depending on the printer.
For all printers, the nozzle should be about ~0.2mm away from the bed (about the thickness of a sheet of paper).
More durable than PLA
Available in 1.75mm and 3mm.
Both PLA and ABS produces fine printing but it should be the application that determines the choice of material during printing.
Yes, TechnoNeeds prints your desired models of choice.
Servicing is available to TechnoNeeds for 3D Printers.