Well fusion makes a mess of the mesh if you try to convert it to work on it directly in fusion. Its best to have simple clean topology. I ended up using blender for the very end to add details i couldnt really add in fusion . its also possible to not convert the mesh and then convert ( they call it tessellate ) your fusion objects to a format that will merge with the mesh. Also for some reason exporting from Blender to slicer shrinks the object , some suggest to scale by 1000x but i needed precise measurements and they were still slightly off opening in fusion and exporting from there worked . Now my dog and i have matching sunglasses 😀 !