What stepper motor to use in heated chamber
"Since it has a heating chamber I can't use normal stepper motor"  Sure you can, the interior doesn't get all that warm unless you really seal it up tight, and that's not really needed.  I have an enclosure around my 200x200x200&nbsp;mm MIGBOT (early Prusa clone with direct drive extruder), printing PLA with 60&nbsp;&deg;C bed, the interior only gets a few degrees warmer.  The motors can take a lot more heat than you think they can.

I have a couple pictures in this thread.

The front &amp; back panels are 18x24 inch polycarbonate from Home Depot, I 3D printed the corner brackets, and added a couple of pieces of wood for some stiffness. The entire front hinges up. The top is 24x24&nbsp;inch, and the back 6" hinges up to access the SD card that is on the display/control panel.