Knect-a-Shelf Connector (Maxit, Gracious Living)

I bought a few of these shelf units to connect together, I wanted to have better connection than just the 4 connectors they include in a package, so I made my own copy of the connector.

I printed without a top layer and no infill and it is plenty strong, maybe stronger than original.
it should be hollow, though i did not design it as a true hollow object, so as long as you select no infill and no top layer it should end up much like the original.

No need for fine settings, Draft is going