Endless Spawning-Footmen Frenzy

How do you make a building that endlessly spawns units every ______# of seconds?

Via triggers. Moved.

Have a periodic event that goes every 10 seconds or whatever, then inside the trigger pick all units in unit group (all units of type "your building"), then for each one create a unit of your choice. I think you could have easily figured that out yourself if you just looked...