This is how you make item reicipes like in dota or hosk and other maps. I thought the easiest way to outline it would be to just make a sample trigger and copy it as text and put it in here, I might rewrite this tutorial.
<div class='triggertop'>TRIGGER</div><div class='triggermain'> Test
Events
Unit - A unit Acquires an item
Conditions
Actions
If (All Conditions are True) then do (Then Actions) else do (Else Actions)
If - Conditions
((Hero manipulating item) has an item of type Blue Print For Sword) Equal to True
((Hero manipulating item) has an item of type Metal) Equal to True
Then - Actions
Item - Remove (Item carried by (Hero manipulating item) of type Blue Print For Sword)
Item - Remove (Item carried by (Hero manipulating item) of type Metal)
Hero - Create Sword and give it to (Hero manipulating item)
Else - Actions
Do nothing
</div>
<div class='triggertop'>TRIGGER</div><div class='triggermain'> Test
Events
Unit - A unit Acquires an item
Conditions
Actions
</div>