I remember seeing most of this awhile back, but can't find it now that I need it.
1) I am making a full sheet cake by putting two 1/2 sheets together. Do I need to put a thin layer of icing between the two to glue them together?

2)I am also making this 4" tall by putting a second layer of 2 half sheets on top. When I dam and fill, I assume I dam the two halves as if they are one cake and not two separate halves? I hope that makes sense.

3) On top of this gargantuan mess will be a 9X12X6 cake made to look like a tool box. I'll be making this using 3 two inch layers. I know from here to put a cake board every 4 inches. So that puts a two inch layer on its own board. After its decorated and is ready to serve, do I just run my big knife under where I know that cake board is to remove this 2 inch layer?

Thanks in advance!

WOW!!!!! That is one gigantic cake!
I hope you have a wooden board to put it on. Even 2 full sheet cake boards, glued together is not going to be enough.

.........need to put a thin layer of icing between the two to glue them together? .......
I don't. I know many say they do but I never did.
........When I dam and fill, I assume I dam the two halves as if they are one cake and not two separate halves?......
Treat as one cake.
..........put a cake board every 4 inches. So that puts a two inch layer on its own board. After its decorated and is ready to serve, do I just run my big knife under where I know that cake board is to remove this 2 inch layer? ........
Yes.

Thanks for the quick response. Yes this is one huge cake! I'm actually putting a 2" lid on the tool box cake, so it will be the equivalent of 6 full sheets once it is all assembled. Oh plus the cookies to go in the tool box!

This is for my uncle's b-day who has terminal cancer and will probably only make it a couple of months if that. He's been going downhill fast. So I want it to be great for him. I think I have a good handle on the cake. I just needed some expert reassurance!

Thanks again!

sounds like good answers and a huge cake

Oh one more question. ON the base board. Do you think that 3 - 4 foam core boards glued together will be sturdy enough? I'll put the toolbox cake on at the church? Or do I need to send DH to homedepot ASAP?

You might consider doing this for the second layer of the base. Think of legos when I describe this. Place one of the 1/2 sheets centered on top of base. Cut the other 1/2 sheet in half and place a piece on either side of the centre piece. The cake will be stronger in the centre and may not bend when lifted. It might even be stronger if you do it the opposite way. Three pieces on the bottom and two on top. Just a thought.

Thats an interesting idea dsilvest. I wonder have you or any others out there tried stacking this way before?

No, I have never tried this for a cake, but I have tried it for other things. It make sense to me because you don't have a weak spot in the centre of the cake that will crack (if you set it up with 3 on the bottom and 2 on the top). If your board is a bit weak it may prevent it from cracking as well.

I just tested my stacked foam core boards with my frozen layers. Yeah, kakeladi....you're always right. DH is cutting me a 3/4 inch plywood base as we speak! Thanks for saving me from disaster!

Thank you guys so much. Here is a picture of the final cake. My uncle was blown away by the cake and his community wide surprise party!

oh my! It's beautiful! Your uncle would love it!