my latest home project

So question regarding the valves. Showed my fiance your work and she thought you did a great job but her only comment was.. Could the valves act as a dimmer instead of on/off? How much more complicated would that make it..

On another note. I work with those valves everyday and I know the internals but I cant grasp how you gutted them and made them a on/off switch.... Just perplexes me