I have a customer who wants a cake with tie dye effects but I don't have an airbrush. I have used the Wilton spray can stuff but not a big fan. Can anyone give me some ideas and tips on how to do this. Thanks!!

What about sponging the color onto fondant. This would allow you to blend two or more colors together to get a whispy look. Or you could try Duff's Grafitti spray color. Might work better than Wilton?

I paint on my cakes all the time. Half of them have painted "texture" and artwork ... easy and fun. Use gel colors plus a bit of vodka to make sure it dries. HTH!

I used modelling chocolate to make a watermelon rind, which is kind of tye dyed with two greens.
You could try doing it with different colours, I would twist your colours together then roll it out, practice first to see what works.
C

Use three or four different colors of fondant. Choose one color as a base color and roll that into a sausage width log. Do the same with the accent colors, only making them 1/4 to 1/3 the width. (Think sausage width for base color, string cheese or smaller width for accents). Align all your logs of color side by side and twist all together a few times. Now that you have one multicolored rope, form in into a "z" shape and roll it into a log. Repeat this one time, then roll out. The marbled fondant will have a very tie dye appearance. Sorry, if it is difficult to understand, I explained the best I could! HTH good luck

I came across this cake recently that is done in buttercream. You would just pipe it on and smooth it.
http://cakecentral.com//gallery/2056219

Thanks everyone for the great tips.

I recently did a cake for a friend. She wanted a torso cake wearing a tie dye Tshirt and big peace sign necklace. I just did the Tshirt in white fondant and painted right on it with Gel color and vodka. It turned out great. I took a plate and put blobs of color on it like an artists pallet. dip brush in vodka and then color, just a tiny bit, then on some scrap fondant or paper towel i kinda rubbed of some of the "paint" then painted on the fondant on the cake. It was almost like a dry brush technique. I also blended with a tiny bit of vodka on my brush. so like if I started with yellow, then did blue, in the middle would be a green. Yellow then red, would have orange etc. It turned out nice.