1st, sorry for all the thingalert msgs, it took few tries before I got thingiverse to like the pic :-P
Yeah, it would be nice to work out the length in an easy way. I just enveloped the thing in a 237mm tall cube and changed ty1 until I got the thing to occuppy the whole length of that cube.
In the example above I said "125" just because is a length that most printers should be able to print.
! I've test it and YES! I can hear the heart of my sons!