Is it possible to make a GUI without using the In-Built Version

I have been playing about with unity-script recently and i wanted to have %100 control over GUI’s which i cannot get using the built in functions. So i’m asking is it possible to make a GUI without using the in-built version. If it is possible how would i go about coding it?

Yes - there are many alternative GUI packages available on the asset store. The inbuilt GUI is known to have several flaws (mostly from a performance point-of-view), and is shortly to receive a complete overhaul, but it might help if you were to clarify what exactly you feel it does not give you 100% control over?