What are your approaches to prototyping?

I always get stuck programming the prototype - too much going on my mind, and I end up losing motivation due to lack of a vision.

This time around I've been thinking in using Blender to create rough sketches of places, mechanics, etc. Since that should give me a fast space where I can test my vision without creating code.

As a bonus, when I get to the implementation phase I'll also have something to work towards and compare!

And that got me thinking, what are your favorite prototyping methods? ๐Ÿ˜‰