first up I had to educate myself on just what ellipses were, so spent the precious evening with graph paper and pencil attempting to scale the same profile for both lengths.
first up I made a plywood template and once I was happy with that made a router bit profile template 

Do I need to offer another Teamviewer session about learning SketchUp... again? 

 a round over bit will be next and its ready for a glue up. 

Why the hell would you want to glue up a round over bit?

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