zabaat,
What you're saying is partly true, until the new CAN library is published. The Atmel engineer that developed a prior CAN API for the SAM3X8H, is supporting Arduino with this CAN interface for Due. Once the library is on github, everyone should start to test/discuss/contribute. And I say partly because at this very moment people in this forum could be contributing, let's say, with the design of the shield. Electric schematics have been published here. I have also shown a couple of my shield approaches. What I would like to hear in this post is: My pseudo CAN shield is ready. Here a picture of it, but I have yet to see any of them here. Does that really matter? Yes, because otherwise, you can't do any test or discuss or contribute just with the sketch or the classes. Am I right?