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
Step 1: Using 123D Design Online
- It is easy to use - designed from scratch to do simple operations well
- It maintains an object "history", so any feature can be edited later - this allows for customization
- It runs in a browser - no need to install software or keep it updated
- Go to http://www.123dapp.com/
- In the Apps menu, select 123D Design
- If this is the first time you've used 123D Design, you'll be prompted to install a plugin
- You should also create an Autodesk account, or sign on with any of several social networks
Step 2: Adding geometry and joining parts
In this case, add a cylinder, make it 20mm wide and long, and 5mm high. Also add a cube, 20x20x4mm.
You should be able to drag them together, and side of the square will snap to the middle of the cylinder.