I did this simple design on my deck. It's strictly onlay, made from 2" edge-banding veneer. Looks pretty good by me.

The one problem I had was that the sharp inside corners were tough to either 'fill' with epoxy or sand into, so there is a bit of waviness to the surface in those areas.

For more complicated designs, do a search for Dave Sprygada. He did some neat stuff and seems to have the technique dialed.

For staining search for Gini and an Arctic Tern, as well as Nick and his S&G Night Heron. Lots of good information and Nick has a good gallery of photos.

Hope this helps

Dan.