Made out of 2mm wood (birch plywood is more stable, but looks not as well as lime wood). Lasercutted, stained and glued together.
So you need a DinA4 sheet of 2mm material and a lasercutter (or a fretsaw and much time :-), staining agent (optional, here i used Aqua Clue 2522 - cherry) and of course glue.
If you want to build it yourself, a pdf file of the shapes is attached.
If you like, apply stain agent with a cotton sheet on both sides of each piece before assembling for a better look.
Then glue all pieces together.
There are four different kinds: One with all corners intruded (bottom), one with all corners extrudered (top, do not glue that tenons to have this piece removable to insert the light) and two rings of 5 pieces (one corner extruded bottom ring, two corners extruded top ring).
The exakt location can be viewed in the cutCAD 3D view or in the screenshot one step before (Hint: it is kind of symmetric, and the left side on the grid is the bottom :-)