I'm making a boss battle in which the boss can create portals to drop bombs (the one's Wheatley used)on the player. I need a Bomb Dropper for this to work but I don't know how to get one.

The easiest way right now is to decompile one of valve's map, since it's not stealing or anything, so it's ok

MissStabby made a great map that has bombs, maybe you can ask her

Basically, I think the bomb dropper is just a cube dropper with a bomb just replace the cube with a bomb entity.

Yes. You just need to build a cube dropper (or anything else where bombs come out) and set the bomb in it. Now just use a point_template to be able to respawn it.

I would have tried that but I can't seem to find the bomb entity anywhere. I'll PM Miss Stabby and see what did with her map.

Actually the bomb is a personality sphere, it is a core that explodes
If you look up the model files and type in angry you can find the bomb

It may be that the bomb is not in the FGD file of the Portal 2 SDK. In my signature you find a link "Improved FGD files". Install it and you will have some new entities and keyvalues/in-/outputs for a lot of entities.
The name of the bomb is prop_exploding_futbol.

MissStabby told me it was point_futbol_shooter, and it works! However, my prop_portals aren't spawning where they supposed to. They both end up spawning to the middle of the map.
Here's what I'm doing, I'm making a boss battle that involves the boss creating his own set of portals. One portal is under a bomb spawner and the other is on a wall to fling the bomb at the player.

You need to set the Prop_Portals by outputs. There is a output called "NewLocation". There you have to give the x y z coordinates and pitch yaw roll for the portal.

http://developer.valvesoftware.com/wiki/Prop_portal

Ok, I got the bombs working and the portals working. I have one more little issue but that's on another topic.