Problems with boolean union


I am having trouble joining this object into one closed polysurface. One open surface has non-manifold edges and I can’t seem to close them. can someone help?

Boolean Union issue.3dm (6.3 MB)

Steven, your example didn’t come with your post. Try again. —Mark

I have just posted it on this thread

hi Steven, thats a wild boolean mass as you call it yourself in the file :wink: if you click on the big part and hide the rest you can use Invert and Hide for this then use ShowEdges and select Non Manifold Edges - one edge shows up. if you explode it and hide the surface covering or involving that edge you see that 3 surfaces are being joined at one edge which so called non manifold. you have to find a way that obliges your creativity of course not to let that happen, either you cut something away or you create an offset.