We provide a study of crowdsourced design based on the popular service 99designs, a website where users create design contests for other users to submit their ideas for evaluation, competing for a monetary amount offered. By quantitatively analyzing a large number of contests, we report on the dynamics of the interactions between contests and designers. We show results on the effects of different financial incentives and contests' properties on the number and quality of submissions, as well as on how rewards are distributed across designers. We find that higher financial incentives do not translate to more effort by individual designers, but nonetheless have an impact on the quality outcome of contests by attracting a larger pool of designers. We also show that a majority of contests are dominated by a disproportionate few designers, which are both more active and effective in the service.