Thank you for signing up to help in the porting effort for FreeCAD and Pyspread to Python 3. Free software projects depend on volunteer contributors like you.
Just to put a stake in the ground, when did FreeCAD start? When did 3.0 come out, along with the announced end-of-life date for 2.7?
https://en.wikipedia.org/wiki/FreeCAD
...Python 3.0 was released in 2008:
https://www.python.org/download/releases/3.0/
...It looks like the port of FreeCAD to Python 3 stared in 2015: