So during my last cake decorating class we weren't allowed to use stacked tiered construction, we had to use pillars. So looking online I don't quite understand the last step of stacked tiered construction. You put a sharpened dowel through all layers and leave it? Won't the dowel show, or even if you cover it, won't it be noticeable? Or do you just assume you'll have something always covering the center/ people won't notice that you covered it?

check out m,y tutes they both describe how to support and stack cakes, they are a wonky and a double barrel tute but they are the same principals
http://www.flickr.com/photos/deliciously_decadent/sets/72157621850372685/
http://www.flickr.com/photos/deliciously_decadent/sets/72157616259103302/

Using the center dowel is only required if you are transporting the cake stacked. If you are assembling on-site, it is not needed. Alternatively, instead of using cardboards and wooden dowels, you can use the SPS system, which is all-plastic and snaps together. MUCH MUCH MUCH easier to use. GSA carries it.