Hacker News Reader

Maybe Antimony[1]?

[1]: http://www.mattkeeter.com/projects/antimony/3/

True. Inkscape, unfortunately, doesn't really understand dimensions. Internally, it uses "px" as a unit, although SVG understands "mm" and "in". Corel Draw is more serious about dimensions and units, which is needed when you're talking to a laser cutter. SVG users have asked for the opposite feature: roundoff to pixel boundaries, instead of floating point coordinates.[1] SVG's internal representation is a text string of a number with a decimal point, but it's up to the program writing the file to decide how many digits to put after the decimal point. And, of course, you'll get rounding errors going back and forth from text representation to internal floating point representation.

[1] https://bugs.launchpad.net/inkscape/+bug/951655

FreeCAD, http://www.freecadweb.org I do basically all my CAD in it. For 3d-print, laser and milling, roughly in that order. For laser/millling you can either work directly with parametric 2d ("Part Design"), or work in 3d and then export 2d outlines (my preferred way).