I draw out all of my previous parts on AutoCAD LT. It a 2d program that outputs a vector file as a .dxf file. Then I import the .dxf file into sheetCam which produces the GCode to drive an XY table with a water jet cutter I built a few years back for work.
The obvious disadvantage using a water jet is the parts are a little wet after cutting but they dry out beautifully. I cut with just water, no abrasives and can cut up to 1/4" plywood no problem.