This will work exactly as required. One caution - DO NOT expect to take them apart easily. I suggest using a hammer banging on one of the extrusions ends and try to drive it off the connectors. Sort of a forced slide if you will. But then again this is what I want them for. Not to fall apart by gravity force (it's the law you know).
V-Slot connector 2014-02-21
Printed part for connecting or bonding two lengths of V-Slot aluminum extrusion