king what type of plastic are you printing? by your temps i would guess pla. the curling is the natural force of nature when the plastic cools. each layer goes down hot, bonds to the layer under then it cools and shrinks which pulls the cooled layers. now multiply this force for "x" # of layers and your part curls. it the whole reason stratasys has heated build chambers. some plastics do it more than others. pla is easier than abs. abs is easier than nylon. madesolid pet+ is the easiest of all. modeling mouse ears/discs on the corners of your print to hold it down helps alot. if your using pla try ditching the kapton and spray a couple good heavy wet coats of hairspray on your mirror then print on that.