Yeah, good execution, simple shape but effective.
The wood is certainly beautiful and the grain/colours did come up very well the way it was finished.
One of the worth enemies of thin wall bowls/vessels, etc, is the outside diameter of the piece, the wider the circle the more vibration/wobble will affect the outer edges of the piece to the point that if rotating too fast, it will simple disintegrate/explode...!
The 5.5" diameter is a very safe size for these thin wall items but I would suggest caution at the lathe speed on anything under 5mm, over the 7 to 8" diameter. Off-course, the type of wood used will determine its success or failure, some woods will allow a 3mm wall thickness up to the sizes I suggested if lathe speeds aren't extreme...!
Basically, any of these items turned carefully on any mini/midi wood lathe, aren't too bad as the lathe limitations will limit the sizes that can become more of a problem or risk so, all pen-turners with small lathes, making bowls and other stuff out of your small lathe is a good way to break the monotony (if doing too many in a short period of time) and experimenting other turning techniques with some investment in a few extra tools and larger size wood, which is easier to find then most people realise.
Green wood turning is a great way of turning, and something that everyone will find at the local dump, local tree arborist, council workers, and neighbours. Trees have to be trimmed and cut down all the time, every where, keep your eyes and ears alert, and make sure that, when you hear the sound of a chain saw going, go to that location without delay, you will be glad that you did, (51% of the time)!
OK, I stop now...!

:redface::wink::biggrin:
PS: Just in case someone wants to have a go at some logs, here is a good PDF file with great information on how to cut logs for making bows, depending on the way you want the grain to show...!
Cheers
George