I love the look of the tall tiered cakes like this one: http://farm3.staticflickr.com/2722/4413745724_173c0f01e5_z.jpg. But I can't for the life of me figure out, if you do this in buttercream and not fondant, how you manage to smoothe it perfectly! I have never seen side scrapers that long anywhere - is there any other trick to it? I figure if you try to do it with your regular 4-5" side scraper you wouldn't be able to get around some sort of line in the icing from the edge of the scraper. Are there really 10" side scrapers out there, or is the only trick to try to hide the side scraper marks as best you can - using the viva towel method or similar?
Go to your favorite big box home improvement store and look in either paint or drywall departments. There are trim guides and taping knives for under $10 that will serve nicely. I have an 8" taping knife and a 12" trim guide. I prefer the "slimmer" trim guide