From the photo it looks like it's basically flat with pockets cut out, if so, I'd do it this way...

Photograph it next to a ruler (make sure you use a longish lens and are square to the object to minimise distortion) or scan it.

Load the image it into inkscape and trace round it manually - also create a box 1cm long by tracing the ruler.

Export from inkscape in DXF format and load that into Cambam.

Clean it up in Cambam (may need to resize using 1cm box as reference), define machining operations and generate the gcode.

Inkscape is free, Cambam is reasonably priced and you can use it quite a few times before you have to pay for it - should be plenty for this project.

HTH
Mark