The other option if you have a good compressor is to use a Vacuum generator and pull a vacuum into a cyclinder.
This way your not stressing the compressor motor or if usiing the Compressor tank has the vacuum reservoir risking the chance of Compressor tank imploding because it's not designed for vacuum.

Also you don't say how small the part is your trying to hold.? Small parts are difficult to hold due to less surface area so you may need a dedicated Jig with better Vacuum seal to maximise the pull down.