As the title says. It would be very useful to have this. Basically a way to add a variable that doesn't show up in the tuning menu. I read an old thread about this where it was stated that it was not added for simplicity. One way to implement it would be to just hide stuff that is put under the category named "Hidden" or something like that. My own specific use case for this would be tires. Tires is something that multiplies fast when you factor in sizes and physics parameters. When you're already up in the 100 range on the parts count from size variations alone, it's not very lucrative to start adding different tire types and multiply this value once again. A way around this is to use variables on the radius and width parameters, and make a generic part that only holds the physics parameters which every size tire can make use of. This is already possible to do, but the variables would show up in the tuning menu which isn't very neat. This is useful for anything where a generic child part needs to inherent any sort of information from its parent. I'm sure there are more use cases for it.
My JATO and ram plow mod shows it well, I had to use variables for the auto-offset system and they now show up and clutter the tuning menu, just simply equipping the mod without adding any parts adds 4 variables to the menu and adding the parts multiplies it with variables that won't even work because they are overwritten by the auto-offset ones... Would be cool to hide all of them from the tuning menu. Also the thing with wheels is not as easy as it seems. Try to make adjustable wheels yourself and you'll see. Simply scaling the radius is not enough to make a bigger version of the wheel. That is the reason why I haven't finished the mod for it yet.
