Sometimes a "casting" such as a table is needed for a
machine restoration...or for other purposes.  A table
can be welded up from 1/2" plate (or thicker) with a 
1/4" thick skirt of appropriate height for the application.
It is important to flatten the plate as much as possible
before welding.  The edges should be deeply beveled to get
as much penetration as possible. Then, all clamping, tacking
and welding should proceed in a way to further flatten the 
work as it progresses.  Finally, the "castings" can be
planed off flat, perhaps with a "period" effect for an 
older machine restoration.