In college, the issued card holders broke easily and were disliked, so I designed a better one. I iterated several versions, each improving on the last. Earlier, my design blocked the face on the ID, forcing removal for checks, but I redesigned it for full visibility of all info. Friends tested it by throwing and hitting it, identifying weak spots. I reinforced those areas, and now, after all the improvements, no one has managed to break this version yet.