Quartz Composer - Apple's "patch-based" visual programming environment. Drag out a bunch of nodes, wire them together, build a neat little GUI. 10+ years ago I'd regularly build all sorts of little utilities with it. It was surprisingly easy to use it to tap into things that are otherwise a lot more work. For instance I used it to monitor the data coming from a USB device. Like 3 nodes and 3 patches to make all of th…
Have you looked at https://vvvv.org/ ? Maybe it's still comparatively too heavy but imho it's not that heavy (cf. touch designer and the likes). I want to play with it some more myself...