This is Makerbot #3978
I put it together at the end of March 2011, and have made a number of upgrades since.
Yet another extruder filament drive (7113) and heat sinks on extruder stepper motor.
An improved x-follower (8625) makes the x-stage a lot quieter.
The build platform is a constant challenge to keep a smooth flat surface for the plastic to adhere to.
I started with the default Automatic Build Platform from Makerbot. It worked great for a few prints before the belt started to split and bubble a bit.
Then aluminum plate (9657)
Then scored aluminum plate, and Kapton covered aluminum plate.
Kapton seems to be the key. Keep it flat, keep it smooth, and the plastic will stick.
Edit: – upgraded the Y axis with a ball bearing mounted Y belt pully and belt tensioner (11515)