Hello cakers. I have a few questions about cake structure of a cake due this Saturday for my sister's wedding.  The cake will be 4 tiers, all 5 inches high. The very bottom tier is a cake dummy at 14 inches. On top of that is 12 inches, 10 inches,  and 8 inches on the very top. I've searched, but I'm having little to no luck at finding a support structure that eases my mind. Please help me! No time to order supplies online. 

I  just did my first wedding cake a couple of weeks ago and was freaked out by the support system.  Questions: are you transporting already assembled? Or assembling on site?  I know the SPS system is a big favorite around here, but you aren't wanting to order supplies but using Amazon Prime there is something like that system that you could try if you have Prime. 

My cake wasn't as big as yours - it was an 12/9/6, but I did deliver already assembled and despite the complete stress, it all went very well. I used poly dowel supports (hollow plastic) in the bottom 12 inch tier but then switched to thick milkshake straws for the 9 inch tier because the poly dowels were so dang hard to cut.  Lots of people I know swear by the thick, boba/milkshake straws and you can either find those at a store or try Amazon prime.  I placed about 6 in the bottom tier, then 4 or 5 in the middle tier. I didn't use a center dowel and I held the cake on my lap and a friend drove (the cake sat on it's cake drum on top of a large, thick glass-type board - that last part just for transport and ease of holding). I had it chilled in the fridge for several hours, cranked the AC and we all made it one piece - phew! 

I don't have experience using cake dummies and especially if it's your bottom tier, but I'd imagine it would all be the same procedure. If you are super worried, I'd dowel the cakes at home, get to the venue early, and assemble on-site if you can. Otherwise, the milkshake straws are very strong - look up placement diagrams online, use your cake boards under each tier of course...good luck! 

A styro base is one of the strongest tiers one can have:)  It will support the upper tiers with NO problems - and you don't have to use any doweling in it.  Yes, in those upper tiers, but not in the styro.  You don't tell us if you need to transport this cake of if it will be assembled on site.  I would not worry at all about transporting it.  Using straws, as katy_cakes said is perfect.  I have found the straws at some fast food places (like McD) are good.  No need to buy special ones :)  Be sure to read the post by K8 "Just say NO"!  This is one of the few times I would suggest using a center dowel through all the tiers when it is all put together - if you are transporting it.    If you want any help/instructions on placement of the straws just let me know :)