Issue with Boolean Union

I am creating a model that needs to be a closed solid. For some reason some parts will boolean union, but others will not. I can’t seem to figure out how to resolve this. Any suggestions would be great! Thank you!
Pattern-Model.3dm (7.0 MB)

Boolean operations will frequently fail when objects have surfaces which coincide. Modify the small objects so that they extend into the large object and then use BooleanUnion.

Thank you, I will try that.