Factor the two halves of the horizontal cut into shared modules so each can be viewed alone (`plan_up` = deck/screen, `plan_down` = cavity), while `plan` keeps the exploded combo. Cut height and gap are now the `plan_z` / `plan_explode` params.
Factor the two halves of the horizontal cut into shared modules so each can be viewed alone (`plan_up` = deck/screen, `plan_down` = cavity), while `plan` keeps the exploded combo. Cut height and gap are now the `plan_z` / `plan_explode` params.