All you need to make these is—you guessed it—felt! I used a few different colors of the 8.5"x11" felt sheets from the craft store (my local store sells them for 25¢ each, so this is definitely a low-budget craft).
For the ice cream, I cut out a couple of long triangles in tan for the cones and then cut a simple "scoop" shape for the ice cream out of various colors. I free-handed the first one and then traced it for the rest of the scoops so that they'd be more uniform. Ice cream is meant to be sloppy, so don't worry about absolute perfection; an approximate shape is good enough. I also added a cute little cherry by cutting out a circle with a stem sticking out of it. If you'd like to, you can definitely get creative and add more details like whipped cream or sprinkles, or maybe an awesome soft-serve if you're feeling artistic. Have fun with it!