I looked for a few clamps that would hold my iPhone to the ultimaker and the ones i found were a bit extravagant. This basically slots on to the bed and the iPhone (maybe other devices) slots straight in to the clams - with a power cable hole too. 

I've just printed this and it could do with the left side clamp for people who don't have a phone case which mine does... But I originally didn't because I don't like over hang.

Its not pretty for my first design but its perfectly heighten for the Time Lapse 7 app. (free) 

The placement is made for print sizes up to 4 inches - so yes i know it cannot fit an entire Z-print with the placement (but i haven't printed anything that high yet. =)

Note: because of the tiny extra weight added tot he bed, please make sure you re-level you bed. i didn't need to, but I'm sure someone 'might' have to a moan about the design and where its placed. But it does the job for me perfectly.