Bonsai Nut
Nuttier than your average Nut
I actually hesitated to post images because I expected plenty of people to say it was not the best material.
Try not to focus on "best material", and focus instead on "what can I learn from this tree". The only failure would be if you worked on the tree for three or four years and learned nothing. Because then if you decided to buy a more expensive JWP you would not be prepared to care for it.
Not trying to disagree with Tanlu, but at least in my experience JWP is almost never grown on its own roots in the nursery trade because JWP roots are not strong and the tree does not grow quickly or vigorously. On the west coast they even go so far as to graft JWP on JBP root stock. Here is a photo of a grafted JWP at the GSBF show (sold for $1500). This graft was done masterfully in Japan - they scarified the upper JWP trunk bark to match the JBP trunk's bark, and even grafted a JWP branch exactly at the level of the trunk graft. It is very hard to see the graft (I wish I had taken a better picture). It is still there - but very hard to see.

Of course if what you love about JWP is the character of the JWP bark, you won't get it without growing the tree on its own roots. Or at least... I have yet to see a convincing low graft where there was absolutely no sign of the root stock's different bark characteristics.