Todd the wood junkie wrote:

before profiling them on the router.

I'd regard this as a Crime Against Timber, to use a router to make
mouldings in walnut.

Walnut is nice stuff and deserves to be made into an attractive shape.
That means a large scale moulding, with bigger curves on it than a mere
router cutter gives you. Find a huge router cutter (expensive and
tricky to swing), a spindle moulder or (my own favourite) an old wooden
moulding plane.