I think it would be cool and (supposedly) not very difficult, to create an app that allows people to design 2D models and put them in 3D, like the one Shapeways already has, with the addition of an option to insert the 'stick' for stud earrings or even the piece used for handcuffs. I think the idea could become really popular and at least I would like to use it (I know it's not difficult to do it myself in 3D but sometimes sizes drive me crazy XD).