Thats a good method silyavski. I would have to put external radius on my part so that they will fit onto the milled hole but that is no problem. My items will be 58x58x24 and roughly octagonal.

How to hold the pieces down? double sided sticky tape?

It will be expensive to mill a new 'jig' each time out of plastic. I wonder if MDF or chipboard will work.

or I could try to re-use the same jig again, I would need to get it very square on the table. I could drill and tap 4 holes in the table bed to mount the jig in the same place ?