Bubble Shield
Steps:
1. Open the oldmombassa or newmombassa map in entity and then go to the bloc tag and find the soccerball, now save the soccer ball's meta. (remember to check recursive and parsed >_>)
2. Open up the map you want to have the bubble shield in and click build in entity. Now locate the folder and load its soccerball.info thing and wait until its done.
3. Now it becomes quite easy...Go to the hlmt of the soccer ball and then change its phmo (do not null!!!!) into something small such as a assault bomb. Now you can walk thru it! yayz!
4. Now you can go 2 ways with this: you can either remodel and skin if you want a cooler one or just be lazy.
Being lazy:
go to the soccerballs mode tag and change all of its shaders to something see through. I would reccomend using something like the active came glass or overshield glass.
Remodeling:
I'll leave that to you

And voila you have a working bubble shield...ish
If you did the lazy way (or not) you might want to open up your model in milkshape and then duplicate it and reverse its vertexes so you can see the shield inside to.
One thing i have not really messed with is how not to shoot out. People cant shoot in tho. So what i did to make up for this was add health to the soccer ball by copying meta from a fusion and adding it to the soccerball.
It also will make an explosion if the fusion coil is in the map.
Now people want to know how i got a generator in the middle...and that is for another tutorial or an add on because i hvent made it perfect yet.
For people wanting to kno about getting health on the bubble shield...here is how you do it.
PICS MB?!??!?!
Adding Health
step 1:
Go to the fusion core on your map or on another map (i would reccomend injecting the fusion core if it is not in the map.) Go to the chunk cloner of the fusion coils hlmt in the reflexive area and now go to each number in the picture and click it in the order lolololol.

step 2:
Now open up the hlmt of the soccer ball and go to the chunk cloner. Now as in step 1. go to each of the things circled and click them in order.

Now wait for this to pop up =P

Step 3:
Now go bak to the soccerballs hlmt and then go to the meta editor

Step 4:
Go down in the meta editor until you see the health/shields thing. If you used the fusion coil then it should be at 15...feel free to change to how ever much you want to make the shield strong or weak.

DONT FORGET TO SAVE IN META EDITOR!!!!!
Mines
These are quite simple that im not even going to post pics....
Add or Duplicate the fusion coil (or any thing like it)
Now in the meta editor of its HLMT go to its health and lower its health waaaaaaaaaaaaaaaaaaaaaaaaaaaaay down. liek 0.000000000001. And WAM!!! done...easy isnt it?
Now you can model it as you please...and if you like you should change its phmo or edit it so ghosts and stuff will make it lolplode intstead of going over it.
Halo 3 Shields
These are also quite easy. For this tutorial i will be using the scarab doors mach.
Just put it in your map you want and null its phmo and place it on the map and you have halo 3 doors that you can walk through! that easy. You can also use many other things but you might want to find better shaders.