You need to print with Transparent or clear filament , the best temperature I have found to make this work is 274c (even though most say max temp 235c they can be pushed without burning effects ) ,the best resolution to print it is 0.19 or 0.14 . After it is printed it will look either white or murky , you need to sand all the top layers off until it becomes clear .Always use a fine grade sand paper and do not use acetone to clean as it will make the clear section white