mel52 
 commented 3 minutes ago 
1. Make 2 separate cutting boards with wood of your choice. Sand faces fairly smooth when dry.
2. Use double sided tape on face side to stick together.... 

I believe, from picturing in my feeble brain, that this is the secret and not trying to matching of curves (if that misconception of mine makes sense). After that snippet of info it seems purely academic...

Thanks mel.   

If your first cut is too short... Take the second cut from the longer end... LBD