Snap Kits are 3D models that include a small bundle of related designs that can 'snap' together in the software in order to customize the project.
Snap Kit Example
One of the free designs included when purchasing an Alta printer is called Design a Duck Kit.
This gives you a duck model for the base and a number of accessories that can be added to the duck prior to printing, such as a bow tie. These parts will snap into place onto the base in the expected location when you move the part onto the base model.
Snap Kit Video
Solid Models vs. Pieced Models
Some designs will print all pieces as one solid model while others may print each piece separately, to be adhered after printing.
If your design is printing in separate pieces but you would like it to print as a solid piece, you can do the following to group the design together:
Open the design(s) of choice in your work area
Snap the pieces together as desired
Click and drag the mouse to select all desired pieces