Have a look at Womp – a new easy-to-use 3D modeling platform that works in a browser. One of the most interesting (and surprisingly satisfying) features is its “liquid” 3D that allows you to goop, melt and subtract shapes with each other.
You can create models using primitives – spheres, cylinders, or cubes – joining them via Boolean unions or substractions and see the result in real time. As for materials, metal, plastic, rubber, skin, glass, and jelly are available now. You can adjust their metalness, roughness, glass, and translucency, as well as lighting.