This is a modification of https://www.thingiverse.com/thing:2573484 - I changed the cross-section shape of the wavy parts from rectangles to ellipses. I wanted to strengthen these parts so there would be less movement when printing the upper sections. The change in cross-section helped some, but the results were still not as good as I hoped for. The net result is that the tops of the waves end up being a bit bumpy.

The good news is the spaces between the waves are nice and clean, so that gave me the desired result of nice light patterns when the LED is on. Also, I decreased the tolerance I used for creating STL files, so the curves are much smoother now. And finally, this lamp is about 10% larger than https://www.thingiverse.com/thing:2573484. It printed in 33 1/4 hours using a layer height of 0.200 mm and a print speed of 100 mm/sec.

The lamp is designed for an LED "puck" light. Battery operated lights are about $4 each; simply do a web search for "LED puck light" to find several sources. This blog page tells where you can get wall powered lights that are brighter and that work very well: http://birkbinnard.com/blog/wall-powered-led-lights/.