I am helping my cousins wife with a couple of 12x18 sheet cakes. Unfortunately the trays I have are a bit too small. So, I wanted to try this foam core stuff that everyone says they use.

Except, I'm not sure how thick? The craft joint has 2 thicknesses. The 1/4 inch and 3/8 inch I think. I didn't know if one layer of one particular thickness would be enough or if I need to stack a couple layers?

The cake is going to be two full layers & a filling. The last time I did a cake this big, my wilton cake cardboard buckled a tiny bit & I ended up with wrinkled buttercream....very irritating.

So - how thick? how many layers? how do I cover it with fondant? Also, how many inches around the cake do you leave for clearance. I may be able to get the two boards I need out of one sheet, just cut in half. But, that only leaves about 1 inch after bc on the sides. Is this the norm in your world?

Thanks for your info or thread references, my "search" skills aren't so great!

As far as how much room to leave on each side, I would leave at least 2" (more depending on decoration). Gives you something to hold on to as well as space for borders or other little frilly pieces.

Also, those are gonna be some HEAVY cakes. I would use the 3/8". Not sure if the 1/4" would be strong enough (and it may very well be) but I would say go for the thicker one. Just my thoughts! People with much more experience might have better ideas. (If they do, I'm always happy to learn what they are!)

3/8 for sure...i use 1/2 inch, but it should be close enough. and yes, you should be able to just cut it in half. i cover my boards with plastic tablecloths (you can find them in any color, they're food safe, cheap, cut to any size, etc.). just cover the board like you would a present i don't think you need a lot of room around the edges of the board, if you're only doing a simple border.

Thanks for the replies! I love the table cloth idea. I have never actually seen this material, so I had no clue how it holds up. I appreciate the advice!

Yup, I'm doing a simple border....I'm thinking rope. It's for a boy scout party. I was hoping just one sheet would be sufficient.

Thanks again!