I treid to make a smaller version of the Octo 4240 lampshade. I started out making a parameterized model in FreeCad to play around with size and diameter, and to determine how many "rungs" I needed. When satisfied, I exported the rung-shape to Inkscape, where I also drew up the bottom plate. To ensure the correct distance between the rungs I also made a ring to fit where the lampshade is widest. I didn't really think the design of this one through, and ended up having to break it apart to get it out of the finished lampshade. After plenty of fiddling, I got all the rungs in place, and glued them to the bottom plate one at a time, and used scotch tape to keep them in place while the glue dried.
The top diameter was made to fit the size of an Ikea lamp-shape mounting ring, which is held in place by a snug fit. I initially wanted part of the light bulb to be covered up by the narrow part of the lamp shade, but this turned out to make stuff starting to smoke, so I sorta decided against that.