Another competition piece. I have never been quite sure about wooden goblets (what exactly are they for!) but have admired some examples. So challenged for one here is my effort. I chose to do the 45 degree cut/veneer glued in 'celtic knot' technique often used for pens, with an additional ring also glued in on the base. The veneers are (white) tulipwood and the rest mahogany. The latter from a single piece, but not made in one piece. So after the veneers are glued in the initially square piece is rounded and the outside of the bowl formed and sanded, but with an additional 30mm or so long by 24mm diameter stud on the base (see pic). The bowl plus stud are then (hand) sawn off and the interior of the bowl hollowed out. I did this because I did not think holding the far (stem) end, as opposed to the stud, would be firm enough for hollowing. Then a 24mm diameter shallow (~10mm) hole was drilled in the end of the remaining stem section which was fitted with a removable plug to enable the stem to be turned between centres. The bowl stud is sawn off short before glueing into the finished stem (with the grain matched up).
This worked OK though hollowing was still tricky - started with a 25mm Forstner bit and eventually, after experimenting with other tools, finished with a 12mm carbide disk tool which could be seen as a hollower. The resulting interior is OK but not perfect - not least because this is all done by feel - one cannot see what one is doing! Some sanding also required. The interior is quite deep to the base (leaving around 10mm thickness at the bottom as opposed to the ~2-3mm side walls) but not all the way down to preserve the celtic pattern as seen on the inside. Finish danish oil (2 coats) followed by microcrystalline wax (all done by hand - not on the lathe).
The result is not perfect - I incorrectly assumed that the larger object would require less accurate 45 degree cuts so did not use the jig I normally would with pens, and the base ring veneer insert is two layers thick which works better than the single layers in the bowl. I could do better next time (if there is one!). Hope of interest anyway.