KenK writes:

I have a big bunch of computer type power cords but very few A/C extension
cords. Any easy cheap way to convert a few? All I can think of is to cut
off the female plug and put on a standard three-wire A.C female plug. Am I
overlooking an easier cheaper way?

Easier? Discard them and buy purpose made extension cords.

If you really don't want to wire a NEMA 5-15 connector to the wire,
you can remove the female IEC 320 connector and use the remaining wire
as a replacement cordset for power tools, appliances and lighting
fixtures.

Note that computer power cords use AWG18 conductors with an ampacity
of 7 (about 800 watts at 120VAC).