Important Note - This video is now slightly out of date for the 1.1.0.6201 release. Mark is updating it soon, however the information within is still good. Just read the release notes for the 1.1.0.6201 release (available in the release thread or on nuget.org) and you will see the adaptations required.
Hey guys, Mark Smith has made a nice video on making custom renderers.
Edit - Disregard following paragraph, he fixed it.
The exact means of implementation for the rounded corners in the video could perhaps be better (we already discussed it and he mentions it at the end) however the general concepts are there and rather than wait for a re-record I would rather get the content out there for you guys to consume and learn from.
So here you go!