I have a friend who wants a 2 tiered cake. Thats great! Problem is she needs to take it 3 hrs away. I have told her i am nervouse about it but what else can i do?
Other than putting a center dowel there isnt much you can do. One thing I have done in the past that worked really well is that I melted candy melts and put a thin layer of that between my layers. Once the candy set up it acted as a glue that helped with the stability. Good luck!
Is she paying for it?
If so, make sure you take care of giving it a good stable structure. Giver her all the instructions she needs for traveling with a cake. Then, if you don't have a contract stating so,(which is a good idea to have if she's paying for it...even if you're friends) make sure she understands that there are definite risks involved in traveling 3 hours with a cake (like being subjected to constant vibration for 3 hours) and that you can do your best to make it stable, but cannot be responsible for how it survives the trip.
As long as she's aware of what she's getting into and is willing to accept whatever happens, there should be no problem.
When making a cake for a circumstance like this, I always try to get them to choose a design that is wider than is is tall. That will improve the stability greatly. A design like this is easily possible even with a two tiered cake.
The SPS support system would probably work well for this travel. You make a hole in the center of your upper cake board, and there is a small peg on the plate that fits into that hole. You would still use tape or candy melts to attach the board to the plate. The legs then "lock" into the plate underneath, so there is no fear of the legs slipping/ falling.