I have a hard time with my plastic extruder. Building it was mostly straightforward but reliably using it is not.

The extruder nozzle, the brass barrel and the PTFE heat barrier, which are the main components of a plastic extruder, did I buy from the MakerBot webshop (took a few weeks to arrive, the German custom is really slow in handling packages...).

As one can see on the picture I built a simple wood construction to hold those parts, drilled some holes for the plastic filament and added a stepper motor plus a ball bearing for being able to guide the filament to the extruder nozzle.

At the beginning the extruder worked more or less flawlessly, but then the nozzle clogged up and the motor stalled.( The PLA plastic tends to do that from time to time as I read. )
I had to learn the hard way that employing manual force to push the filament through the extruder is NOT a good idea.. I pushed the brass barrel out of the ptfe barrier (PTFE expands when it is heated up) and ruined the threads inside of it.
As a quick fix I added a nut to the brass barrel and glued it onto the PTFE with JB Weld.

But after really little use the adhesive joint broke apart.

Here are two pictures of my print results so far. I tried to print a Shot Glass that I got from Thingiverse.

The bad quality of the prints was mostly the result of software issues (irregular movement of the extruder stepper and a bad ration to the feed rate, loss of the serial connection etc).
I think I fixed most of those problems but can't really verify it till the extruder is working again.

Today I ordered some raw PTFE that will hopefully arrive soon. Once I get it I might be able to fix the extruder and get back printing again.