My kids (ages 4 and 6) also loved the Cub's Den craft activities in the afternoon. I mean LOVED them. We went 6 times during our trip this past summer. They would choose to go to Cub's den after lunch rather than staying in MK. Can you imagine that?
It is a great place for the little kids to de-stress, get out of the heat, and do routine stuff like they would do at home. Some of the crafts seemed to be kits from Oriental Trading Company and some were craft ideas from other sources. There was only one craft that the 4 year old needed some parental assistance with. They will bring out coloring for kids if they're too young for the craft. The CM's there are wonderful and my kids enjoyed talking to them.
Cub's Den is one of the reasons we keep going back to WL rather than trying new resorts.