I recently had to design a set of objects to distribute at a technology event, made to be easily 3D printable and customizable, ideally by people who are not very familiar with 3D design software.
One useful small item is a customizable key tag, big enough that you don't lose or forget important keys.
Given my background with consumer 3D printing, I set out to design an object that would print really fast, and would look nice.
If you want to save time and see the final result: Edit the keychain in 123D Design Online
You can also use the gallery link: http://www.123dapp.com/smb-123D_Design/Keychain/1264529