I spend about 6 months building a 3D printer. The printer is based on Prusa I3 Rework, and then later modified and upgraded. The upgrade includes a more compact extruder unit ( Titan extruder module ), and height-adjustable Z-endstop ( saves a lot of efforts leveling the heat bed ). All parts as well as the raw materials are purchased separately, self-cut, and self-assembled.

I've also built an enclosure, to better keep the temperature while printing ( which saves me on electricity bill ), also keep me away from the plastic smell. One key of the design is the drawer rails which support the printer such that it can be pulled out for maintenance or cleaning. Spool is also installed on top, and LED lights increase the visibility while in the dark too.