I've made fondant/gum paste figures before, but how do you make them standing up like in this photo? It seems like the weight of the body would squish the legs
It really depends on the size of the figurine. For large ones I use a wire armature. For smaller ones I use 2 lollipop sticks that run from about the waist of the figurine, all the way past the end of the legs. The excess acts as a stake to stand the figurine into the cake.