I am a novice to Blender and 3D-Printing. My Kids love Paw-Patrol and I found a bunch of pretty detailed models that I could print for my them. The issue is that the designer overlaid a bunch of meshes without merging them when creating the models. When I bring them into Cura to slice, this issue is revealed with holes and missing layers. The print doesn't know where to start and where to end. I tried to use CTRL L, create vertex groups, split them into individual objects, and use the bool tool to join everything, but it didn't work. How can this be accomplished? I can eliminate all the internal parts that don't matter to the 3D print, but that doesn't solve the overlap of all the groups found on the outside. Here is an example: https://cults3d.com/en/3d-model/various/paw-patrol-rocky.
Thank you for all the help given here. I have really enjoyed learning Blender and working on these kinds of projects.