One issue that I ran into was I made a mistake in the first sketch that I made of the saddle. Unfortunately, the way I set the constraint, messed this up and took a while to tidy up. To draw the saddle, I need the sketch for the sherline base. The thing is that the changes made to base to automatically propagate to the next level.
I think I want to study basic file structure to the fcstd and where things are at with freecad Assembly.
I need to go through this in a bit more detail. http://sourceforge.net/apps/phpbb/free-cad/viewtopic.php?f=3&t=3072&hilit=volume
Also a friend on the IRC was looking to have freecad calculate out a counterweight balance.
It seems like you would need to be able to extract out the volume of a solid…
I found a link on calculation surface area of a solid: http://sourceforge.net/apps/phpbb/free-cad/viewtopic.php?f=3&t=2913&p=22383&hilit=area#p22383
Some suggested reading from the IRC https://sourceforge.net/apps/phpbb/free-cad/viewtopic.php?f=10&t=3157