This is an experimental design where two cylinders can be joined by attaching this object to the model in question and then injecting a filler material to bind the two halves together. Its useful because you don't need screws, just glue, acetone ABS slurry, rose's metal, etc to bind with itself. The inner pathways allow at least a mechanical connection that should be strong enough.

I have not yet tested it yet but the object is parametric and should be printable by a RepRap.

The way it works, is that you connect two cylinders together by putting together the ends and filling every other hole along the seam. This should produce three filled holes with non filled holes in between. This should block air passages and allow the second filling to push material throughout the entire structure, hopefully without too much back pressure pushing material out. If this is the case, then the first filling should be left to sit for an hour or so or can be baked to boil off the solvent. Once all the holes are filled and the piece has been set to cure, it should give a satisfactory bond.