Pimp your IKEA LAMPAN with Inkscape
You can easily pimp your IKEA LAMPAN by adding a paper cutting inside: The Math First we have to do some math. The lampshade is a geometric shape, a truncated cone. The pattern is part of a circular ring, i.e. a circular sector from which a second sector is cut out: The theorem of Pythagoras gives m = √ h²+(R-r)² and from the theorem of rays we get the equation R/r = M/(M-m). Thus: M = m-R/(R-r) applies. The sketch also shows: 2R-π = 2M-π-(α/α) and from this follows α = 2π-R/M - that is 360-R/M degrees. With this information you can create something like this in Inkscape: Bending a rectangular You can now start editing. But I like it more to work on an rectangular shape. Therefore I'll add some helping lines. I insert an additional node on the left and on the right: Then I create a centre line as helper for the next steps and use the extension "Draw Handles": I changed the colour to grey to make the handles more visible: Now I can start t