Once you've created a visibility state for every combination, you have to choose one or other for the user to select first. These notes are based on choosing "horizontal" first, but it should be easy enough for you to adapt to do the other way round!
The screen grabs I'm posting here are for one I did for a sofa. You select the number of seats then select a corresponding activity zone type.
Create a Lookup table to select your horizontal scales. Set your Input Property to the Visibility selector and choose a default state for each horizontal scale. On the right-hand side, you enter the text you want to appear in the drop-down menu (the horizontal scales). MAKE sure that you enable "Allow reverse lookup".
You then need to create another lookup table for each horizontal scale.
Again, select the Visibility action as your input, but this time you need to select the states for all the vertical scales available at that horizontal scale. On the right hand side, you again enter the text you want to appear in the drop down menu (the vertical scales), again, make sure to enable "reverse lookup."
Make sure you constrain the visibility of each "vertical" lookup table to only appear in its relevant horizontal scales.
I've also uploaded the sofa block I created - looking through that may well help you.
Could someone tell me how to get the images I've attached into the post please?!?
dJE