I am not sure if this is a well known thing, or a newly discovered way of playing the game, but I think there might be a good way to make TVC for solid rockets without mods. To do that, you need to attach two hinges onto each other, and twist one of them 90 degrees relative to the other. Assign the control to pitch and yaw, and limit the range to 5-10 degrees. Turn on "Fuel Line" under the "Additional Settings" panel, and attach them to a fuel tank on one end, and a motor on the other. You might need to invert one or both of the hinges to make the engine turn in the direction you need. Voila, now you've gotten yourself a functioning gimbaled solid rocket booster nozzle!
