Hi THere
I'm new at the creative cake making concept ... however I would love to tackle a castle cake for my daughter's upcoming birthday. The cake itself I pictured as each layer being a different pastel color. I found a suggestion to add a package of desired flavour and color of jello gelatin added to a store bought white cake mix. Could I use that idea with the cake mix extender recipe found on this website. Will the cake be strong/ dense enough to stack? I guess It' best to still to secure it with lollipop sticks or dowels? Suggestions welcome!!!

Welcome to Cake Central!! This is the doctored recipe I use and have used it in stacked cakes. It's not terribly dense but it works well because all the tiers are the same density. This isn't a recipe I'd use if the tiers are to be different like one tier carrot cake for instance (it's so heavy) I use:
1 white cake mix (I use Pillsbury)
3 egg whites (eggs should be room temp)
1 whole egg
1 small box white chocolate instant pudding (I many different flavors depending on what I want.)
1/2 cup vegetable oil
1 1/4 cups water or water/milk mixture
1 tsp almond, vanilla, whatever extract you may want to use

Bake at 350 F until it springs back when lightly pressed.

You definitly want to put each teir on boards and use dowels to support the tiers! Also dust a bit of powdered sugar on the area a tier is to be placed so the icing doesn't stick to the board when the cake is taken apart to be served.

Can't wait to see your creation!
Dori

I think your idea for the pastel cakes would work fine. Make sure you have the cake doweled properly! Those cakes can get heavier than you would think, especially if you're filling and torting.

Yes, I only use cake mixes on all my stacked cakes. Helen

I use mostly cake mixes for my stacked cakes...as long as you dowel properly then you will be fine. Your idea sounds really cute.

You should be fine if doweled properly. You might want to check the box sometimes it gives a idea on how to make a lighter sponge.

Noticed this was your first post and just wanted to welcome you to Cakecentral!