Open gaps but still indicated as a solid

 From:  Timir (TIMTAB)
10674.1 
Folks,

I have been practicing once again to become proficient. I have been using a series of tutorials from Arrimus 3D. The real Arrimus, not the other one.

I was using the mirror image command on this one model and I kept getting a small rectangular opening in the bottom of one of the halves after combining them as one using the Boolean Union.

I tired a couple of separate orientations of the mirrored image for this part and then combined them but all with the same results.

Even with this small rectangular opening in the bottom once the two halves are combined it still registers as a solid when picked.

I can send you the model somewhere for testing.

TimTab