I printed this from ABS because I wasn't sure how hot it gets in there - PLA is probably fine but I didn't want to risk it. Works great.Print it as shown (which is upside down) as it prints better like this with the gradual overhang instead of sudden overhang inside.The flip it over such that the teflon hits the sharp shelf.  I recommend printing with one (1) line of brim and then it locks into the aluminum nicely.This is designed to be the right length for the Olsson block but without the i2k.  If you have an i2k you want to print this slightly shorter.  Just put the stl file into Cura, go to SCALE  feature, unlock the 3 axis, go to absolute mode (versus percent mode) and reduce the length by the thickness of the i2k.