At this point we had a bank of ideas addressing various problems. While an idea might solve one problem, it could be less effective in solving another problem. In some cases, it may even be a hindrance. For instance, the idea of manufacturing the Post Box in stainless steel only deals with the criteria of making the new Post Box rustproof and strong. The joints of the top of the Post Box would still have to be welded, and this would be a potential cause for leakage of water, thus not meeting the crucial criteria of keeping the Post Box waterproof. Likewise, it also increases the product cost. Hence, different ideas are combined to arrive at concepts, which would address all the issues listed in the product brief.