Hero 'Build' Ability Trouble

I'm making a map in which one of the heroes I want to be a builder. However, I have run into a few problems whilst trying to figure out how exactly to make him, well, build.

My first idea was to use the spellbook ability, make it a hero ability, and change the icon, etc. For the spells inside of it, I used 'build tiny' whatever and changed what it built. Then for each level of the 'builder's manual' I would make different abilities based off of 'build tiny' whatever and put them in the spellbook. However, this didn't work. I guess because the 'build tiny' abilities are all on the same order string or something. Whatever it is, it made it so that every ability based off of them built the same thing, not different things.

My second plan was just to give the builder the ability to build structures, and put in the right structures. However, I wanted the structures to be an ability. For example, you level up, learn an ability, and then new structures will be available to build. However, I wasn't able to find a way to modify what structures could be built by a certain unit. I tried looking through all the 'action' triggers and none of those had anything.

Any help would be greatly appreciated.
-Z

if you are wondering how to change the structures built by a unit, which is what i think you are asking you need to go in the "Object Editor" rather than doing it with trigs i hope this is what you want

I know how to change the structures built in the object editor, I just don't know whether or not there is a way to change what structures a unit can build via triggers or JASS after the game has already started.

use trigger search function and search vor construction
My we is german so i dont know the exact name but if you search construction you will find one trigger that allows to disable/enable building avaibility

Well your spellbook ability would work quite well for what your doing, all you have to do is change the order ids of each ability.
You see, when you build something the order id is the name of the base unit of the building. Eg you may have a custom townhall but the order id would be 'townhall'.
So simply go through all your abilites and change the order ids to different buildings.