I wish I could do marquetry. The handles that have multiple colors like #30 (purple & yellow) or #23 (Red-black swoosh) are made by cutting the curves, sanding (and sanding and sanding) to fit them together, then glueing with Titebond III waterproof glue. I make a block of multiple colors, then cut to size for the handle. On ones like #20 with the spots, I drill shallow holes in the handle then insert a piece of wood it cut out using a plug cutter. On #20 I used Smoketree (a yellow-wooded local tree from the cedar glades) to make a yellow spot, then I drilled a smaller hole in the yellow spot to add a black Ziricote plug. I show my steam box and form for steaming and bending the frames on my website.
And nice cup holder. The ash made some nice figure. Jeff