Rainbow Cookie Cutter -- enhanced printability

I had trouble printing the original file in PETG due to massive nozzle pickups resulting in crazy stringing. The problem was that the nozzle travelled like crazy through the already printed parts of the model due to the uneven wall thicknesses leaving tiny gaps to be filled once the walls were drawn. I completetly re-designed this resulting in a much better printability (and also speeding the print up a little).