In Reaktor 5 one could do reasonably rapid prototyping with one of two macro collections provided by NI. Both the building blocks collection and the classic modular collection of macros behaved similarly to blocks, they just aren't quite as sexy looking, or sounding.
Since blocks are new, there's still a lot of room for improvement in the diversity of available tools. For example, there were some very flexible and complex tools in the aforementioned collections. One that comes immediately to mind is Erik Weigand's multi breakpoint envelope.
I converted this macro to blocks format, which wasn't too bad since most of the heavy lifting in Erik's macro is done in a core cell. However, it's no small task to get all of the bits of the new user interface elements lined up, something that I wish NI would work on improving.
I've added modulatable time scale and shape factor, added switchable velocity sensitivity, and change the color scheme to be similar to the bento blocks.
It's free for Reaktor users and you can get it in NI's User Library. Please feel free to leave any comments or feedback, bugs, issues, feature requests, either in a comment here, the user library, or in NI's Reaktor forum.