Not a clue, several objects 18mm thick and of varying sizes?

[Nthkentman]

I use Vectric V Carve Pro to design shapes and other stuff in MDF or wood. Usually 2d, but your suggestion of laminating to create a 3d result and then hand finishing would be achievable.
If you were to scan or make a photograph of one of your existing templates you can pull it in to V Carve and using the trace feature you can then make the "Picture" into a new template of any size. Turning that "Shape" outline into vectors for editing is a one click process. (Exportable as a DXF file if you need anyone else to machine it)
Once saved at the dimensions you require it would be easy to make smaller copies using the copy and paste function, then resize using the object size function.
Once you have decided how many to copy the next function would nest them onto the sheet represented in the software.
Obviously readjusting a few vectors where required would be necessary for the various sizes and this will take a little time. But once they are made the cutting out will be a breeze and every time identical.

Have a look at http://forum.vectric.com/ and see if anyone on there has done similar. Very helpful people and the software is a doddle to use and very comprehensive

[EddyCurrent]

You can also use the open source free software Inkscape to trace an image and output to dxf.