Apply a radius to sharp corners of a path. The extension is written for inkscape 1.0.1 (but also contains a backport for 0.92.4). Usage: The screenshot demonstrates the usage. In the upper half, a red path with 4 vertices is shown. We select two vertices: the top left and bottom left corner (shown in blue). Run "Rounded Corners" from "Extensions" -> "Modify Path". The result is the path below. (Viewed here in edit mode again to show all the new vertices.)
This Inkscape extension transforms an object along the x-axis. The bounding box remains unchanged. Points near the center of the object move to create the illusion of a curved surface. Points move left, if you choose an exponent > 1, and right if the exponent is < 1. An exponent of 1.0 does exactly nothing. This can be used in combination with the bend path effect to create a cone projection that retains aspect ratio. Idea from Simon Budig while preparing for the lampshade workshop.