auto cast build units

i need an autocast spell that builds units. the purpose for this spell is so that a player can have a building automatically build units continuosly.

i've tried to edit some autocast spells, but i can't quite get them how i want them.

its a trigger

event - every # seconds

action (ill give you a few depending on what you want)

unit group: pick every unit of type (your unit) and do order picked unit to train/upgrade to (he unit oyu want trained)

unit group: pick every unit owned by (player) and do order picked unit to train/upgrade to (he unit oyu want trained) (<- this one only works if only one building type has that unit)
Unit - order (your unit) to train/upgrade to (the other unit) (<- this one only works if the unit is pre placed in the world editor)