Also I should warn you that this is an extremely time consuming process and you should probably get it done while it's still kind-of hot outside. Mine took me about 2 weeks to finish but you can probably cut it down to about 2-3 days. Probably more like 5 though. And one more thing, when you're done, the cake won't be edible.
Step 1: Materials
For The Cake*: 2 chocolate cake mixes. (You will have extra so you might also make Portal Cupcakes. Or you can eat the batter cause thats what I did.)
Whatever It Says You Need For The Mix
1 or 2 Nine Inch Round Cake Pans (You're making 2 cakes)
Old t-shirt or long piece of cloth (Recommended)
For The Outside Stuff: 1-2 Tubes of Loctite White Adhesive Caulk (better safe than sorry! go for 2 tubes of the stuff)
1 Big Birthday Candle (You can look at the actual picture and decide)
1 Box Chocolate Rice Crispies (I recommend the cheapest brand)
Plastic Knife (Optional)
Fake cherries (I found some in the Home section of Target)
1 Bottle of Espresso Brown Satin Finish Spray Paint (Lowes or Home Depot I think)
1 Bottle of Spray Lacquer
A Medium Size Phillips Head Screw Driver
A bunch of spare time.
1 Bottle of White Spray Primer
1 Bottle of Orange Spray paint
Scalloped Cake Base Things (Descriptive right? I got mine and Joanns and you can decide on the size. You should probably go for the medium/smaller size.)
* Alternatively you can use the polymer cake method. I didn't because I didn't see it until the day before I published this. Using the polymer cake method bypasses steps 2 and 3.
Step 2: The Cake Part 1
You can put it right in the oven, just try not to set the pan on the end strips of cloth. Also if you don't get it wet enough, it might catch on fire but that has never been a problem before.
Step 3: The Cake Part 2/ Dehydration
Method 2: Set your oven to its lowest temperate on convection bake, you can use regular bake if you don't have that setting. Then place the first of your cakes in the oven for 4~6 hours. Use a wooden chopstick/skewer to poke the cake, it should be difficult or impossible to puncture when it's done. Another test is if you pick it up by only one side it shouldn't break in half.
After that cake is finished make sure to put it in a dry area, or better yet if you have 2 ovens, just put it in the other one. Repeat the process on the second cake. Note that you should never put 2 cakes in the same oven because they will absorb eachothers' moisture!
Step 4: Sealing the Cakes
Step 5: Frosting the Cakes
Now, working quickly, spread some caulking over the top of the cake. Then take as many handfuls of rice crispies as you need and press them on so they cover the top. Repeat the process on the sides of the cake, I recommend going in sections.
Once that's all done just go around and blow off any loose crispies and fill in the areas that still look empty. Now you really should wait another day for the entire cake to dry.
You will want to stick a nail in the hole you make in the caulking tube so you can use it in a later step.
Should look about like this.
Step 6: Making the Base
Step 7: How Long Have We Been at This Now?
Step 8: A Cherry on Top
Once that's dry put the candle in and let it burn a little just so it looks good. Now measure around your cake to symmetrically place 8 of your fake cherries on top of your cake. What I did was I put a small blob of caulk where I wanted the cherry and stuck it on. After that I went around the base of each cherry with the caulk gun and made it look more like the actual Portal Cake.