Hi Nick, well one thing I notice at first is that your paw surfaces seem to be made up of a lot of little flat facets, like this area here is a bunch of little fragmented flat pieces:





And for example this little piece here which would ideally be made up of something like 6 faces is instead actually made up of 43 faces:



How did you go about creating those paw pieces, did you possibly use some original imported curve from a PDF file or something like that? If so you might check that file to see if it has actual curves in it or if the things that look like curves are actually just polylines with a whole bunch of little segments in them to make them look as if they were curved.

You generally don't want to directly use dense polylines like that directly as the basis for surface construction, you'll want to get them to be actual smooth curves so that you don't end up with things like small pieces made up of 43 little faces when just a few curved faces would make for a much cleaner structure.

A cleaner model structure would definitely make it a lot easier for the boolean mechanisms to do a good job - it's much harder for them to make sense of so many little slivery bits like you've got here.

I'd also double check to make sure you don't have any pieces that are so thin and slivery that they actually make for a kind of degenerate self-intersecting solid, anything that has totally collapsed degenerate surface fragments in it will cause difficulties with intersection calculations.

- Michael