My daughter wanted a Tinkerbell cake and saw a picture of a really complex one that you had to buy a kit for. After looking at it, I decided it was too expensive and too complex (required airbrushing and was 3 layers complete with waterfall and pond) and that I could come up with something she would be happy with but that was a lot easier. For this Fairies Cake I used a 16" oval tin as it was a large birthday party and it easily fed all the kids and adults.
I had also seen cake decorating Tinkerbell figurines, but they were really expensive (about $38) so I got onto eBay and found very similar ones there for under $7 incl postage. I chose the Tink that I wanted to use (there were 4 in the set) plus her 2 friends and set about building a woodland, fairy scene complete with pond, which is what my daughter had really liked about the cake we had seen online. I bought sugar flowers from a local supplier, they were really reasonable and although I have made them before, with a 3 year old to keep entertained, I certainly didn't have the time to do it myself these days!
I also used a mini yule log (left over from Christmas) as a log to sit my Tink figurine on. The cake board was covered with a wrapping foil I found that had butterflies on it, which worked well as there were also sugar butterflies on the cake. The leaves were all piped using the leaf tip on my piping set.
My daughter loved her cake and it only took me about an hour and a half or so to ice/decorate, which I am sure is a lot quicker than the original choice she made.