These were rendered with Terragen. I like landscape creation software and this one is especially good at rendering clouds. Terragen is fully procedural, as opposed to many other image based programs. In the VRtual X section you can see some other landscape projects I worked on.
These shapes were my first experiments with python scripting for 3D software. Back then i used The Foundrys Modo. I already had some programming experience. Since then I did a lof python programming for the inhouse VRtual X blender addon.
Abstract 3D art is fun. For the fractals I used Mandelbulb3D, a very very very wonky piece of software thats fun to play around with but super hard to learn. The interface is absolutely terrible.
These models were done following Vaughan Lings Blender tutorials. The original design is his, I changed only details but modelled everything myself. You can find them on his gumroad: https://vling.gumroad.com/l/Blender_For_ConceptArt