Let me again mention the Shapeoko CNC mill. Having no serious prior mechanical experience beyond using a drill press and hand tools, It took me a while to get comfortable with it. But now I find it very handy, and use it for all sorts of things -- street-number sign in wood, engraving aluminum, milling aluminum front-panels (holes and recesses), HDPE fixturing to help with other jobs, etc. Once you get it set up you can quickly run off many copies of an item (if you so choose), and even doing one-off work goes pretty quickly. This is an X/Y/Z-axis machine, so some shapes are easier than others.
The Shapeoko is a mid-range unit, using belts for X and Y, and a lead-screw for the Z axis. All are driven by servos, and it's rigid enough for my needs. If you are only going to work with plastic you can probably find a less expensive machine.