If you glue 4 triangular pieces together you should get the look you want. I don't think the corners would be prone to dings with the design you are planning than if you used solid wood. The advantage of gluing up four pieces is you can leave a wire way up the center of your pole.
I made three of these lamps by gluing up two pieces of oak with grooves up the center line. I didn't care for the sharp corners so I chamfered all the edges of the various pieces. You can make the chamfer as small or as large as you like.
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