This is a component meant to be joined to another 3D model so that you can insert a nut and mount it on a tripod. You could stick this on one of the many phone cases here on Thingiverse, for example.
If you are not comfortable with 3D modelling software you can just use MakerWare to print this so that it's slightly overlapping another object. I tested this process and "designed" a tripod mount version of http://www.thingiverse.com/thing:76286 in about 2 minutes. It's almost done printing now.
This nut adapter is designed with a little clip to stop the nut from falling out.
You should probably print one by itself as a test to make sure everything fits. I designed it for ABS shrinkage but it shouldn't be too loose in PLA.
Use 3D modelling software to attach this mesh to another object. Print with the large rectangular opening up, as it is oriented in the provided files. Insert a 1/4" - 20 nut all the way in.
If you are using MakerWare start by adding this nut adapter to the stage along with another model. Position the adapter by rotating it around the Z axis only and moving it so that it's slightly overlapping the other object. Both openings of the adapter should be accessible and the amount of overlap should be less than 1.6mm to prevent the other object from intruding into the internal volume of the adapter. Check to make sure that the adapter does not intrude into important spaces in the other object. Print. Insert a 1/4" - 20 nut all the way in.