I had already ordered a couple bottle clamps so will use those up top and their chain setup down lower. My bottles may last years so having them clamped up is OK, it might really honk off a person that needs to swap a bottle every day. Kinda thinking I may make some T handle threaded devices to use instead of the SHCS they include. These have an M8 thread. Might make 5/16-18 female threaded parts, that portion of the project can maybe wait though. I am going to make 1/4" steel plates to go on inside for the bottle retention stuff. Picturing a bottle with the valve broken off carrying the whole cart over into the next state airborne makes me wary of anything "less than" when it comes to securing the bottles.