Ask HN: How do you visualize complicated problems?

I've been struggling to find a medium that works better than a piece of paper and a pen when it comes to visualizing my ideas, especially when programming. I can usually think through a simple problem when there are a few components involved but once I start losing track of things I need to write it down.

The problem is I end up with all these sticky notes around my desk with small diagrams. I like things like draw.io, but it's just too much sometimes for a simple sketch. A Wacom tablet would work great (especially using mypaint) but, it's a bit much to buy to have to take out and plug in every time I want to make a simple sketch.

What do you all usually do?