layers:   how many rows of bricks

run:   how many bricks in each row

brickwidth:   individual brick width

brickheight:   individual brick height

brickthickness:   individual brick thickness

mortar:   width of mortar lines between bricks

mortarthickness:   thickness of mortar

shift:   start row has halfbricks on ends

rand:   rotate each brick a random angle between

chamfer:   bevel edge of bricks

modeling_scale:   The modeling scale of the .stl file. Specifies the denominator of the scale, e.g., 1/87 for HO scale, the default. Assumes the dimensions specified in the previous parameters are prototype, e.g. 1:1. 
printing_scale:   Scales the model for printing. Default is 25.4, the multiplier to convert decimal inches to millimeters. 
filename:   Enter a name to use for your .stl file, minus the .stl extension. 