A clamp connector to connect two smaller clamps with the purpose of extending the reach. For light duty jobs. Yes, there are easier and quicker ways of doing this but this solution has the advantage of a one handed operation, when roughly adjusted. That's beneficial for glue-ups. Once clamped you can replace the connected clamps with something else for more strength( if needed). This makes it quick and easy to get stuff positioned right. 

When using it, you get more stability and clamping force, if you are able to lay the connector against the surface of the clamped object. This prevents flex.

I printed this one i PETG, 25% hex-infill, 4 perimeters, supports on build plate only.

FreeCAD source files included, as per usual, if you need to modify anything. Try out FreeCAD 1.0, highly recommended.