You will soon find that some brands or lots of cases moon and demoon more easily than others. Some aluminum Blazer can be difficult even with tools. When I first started shooting with moon clips in the 80's, I always loaded moon clips by hand, without tools, and never had a problem. I would demoon with any aluminum or wood dowel the right size, occasionally even a large pencil.
The tools are certainly easier/faster, but some cases are just more difficult than others.