It was one real full day.....and then some. That's not counting my time for doing the research and drawing the art work and getting it into a program I can work with. And then looking for the right inlay materials.
I don't know if it's a trick or not but there's a bit of a method in choosing the right inlay materials and letting them work in your favor. If you look at the palm fronds you'll see that most of the lines run in the direction of the frond, giving the impression of ribs. Of course this is tricky as the layers of shell shift as you sand through. So you need to look beyond that first layer. Same thing with the air plane, the piece of black pearl shell I chose for the under body was much darker in the beginning but I knew it would lighten up as I sanded it. (Both pontoons are the same color, it caught a reflection when I photographed it.) Again, with the koa palm trunks, I let the curl give it the right texture. The red composition stone had black veins in it and I let those suggest the petals of the hibiscus flowers. If it were solid red it would be rather boring and comp stone doesn't accept engraving well. The pistils however were a challenge. The yellow "stem" part is yellow dyed wood purfling, sanded and cut to shape. The little yellow dots.....well, I can't spill everything! My point is, when you choose the materials carefully, half the work is done for you.
Sorry, probably more than you wanted to know........