on the other hand, http://www.openscad.org/ is kinda nice...for simple things :)
But I haven't pushed "Vraag Construct" yet. Maybe in a week or so.
I set my object measurements to variables, then define thicknesses as variables and use math plus union() and difference() while creating modules (c functions) of the various stages that nest in each other.
It can get pretty hacky sometimes with the nested translations to center things relative to each other but it's a wicked awesome way to model.