freecad
tutorials
Sheet metal plugin
3D navigation
- Set '3D navigation' to 'touchpad' in Preferences
Draw a rectangle
Extrude
- use the 'Draft' workbench and 'Trim or Extend' to extrude a face
- or in 'Part' workbench use 'Extrude'
- ... more ways to extrude: https://www.youtube.com/watch?v=jlmd5_lnwXM