Allow toolchain creation without having the blocks first

When I want to create an experiment on BEAT, the first thing that I want to do is to create the toolchain. Creating the toolchain allows me to visualize what blocks I need for the experiments and how they should look like. It was possible with the v1 editor to create arbitrary blocks, define input/outputs and connect them.

The new editor, only lets you create blocks that already exist. But, I don't have the blocks yet and I don't exactly know how they will look like till I draw the toolchain.

Maybe a free editing mode can exist in the toolchain editor?

What I have done so far is to draw the toolchain on paper/in my mind, implement blocks, and then draw the toolchain with the app.