Trigonometry - what a concept!  A little trig and some mathy stuff splashed in there for good measure goes a long way in this OpenSCAD approach to making Christian Crosses.  Change the numbers at the top of the OpenSCAD file to create different (and quite varied) cross designs, or just use the STL file as is for a really pretty cross.  Looks great with a 1mm nozzle (shown), probably looks even better with a 0.5mm or smaller nozzle.  Print time just under 2 hours with 1mm nozzle.