Add a dummy SPlit at the lateral sides to make extrusions (the fork tines).
Make extrusions on perimeters! So kill inbetwenner faces !
Separate/Join when a subdivision is made!
Close a hole with successive snaped extrusions!
(here one by one because intervals are not the same! So no possibility to use array! )



You will have a solid at the end!



Of course not yet so fluid than Rhino 7 but funny! :)