alt Hacker NewsThe common approach is to take a photo of an object from above together with a ruler or something of a known size for scale, then import that directly into the CAD software, scale according to the scaling object, and create a cutout along the object's outline. No need for calipers, 3d scans, or other complex measurement procedures. There are a lot of videos and guides on how to do that.
This is how to do it.I also round the edges of the cutout.
Also, there is an extension for freecad to make non rectangular (e.g. "p") shaped bins.
Most satisfying, least productive things I've done this year!