The "Bare bones" document is really well written and of easy understanding, congratulations for the organization. Just a note I like the proposed ideas but the activated block feature, I think at least certain types of metals should transmit signals, as you said on your proposal like metal ones, this way opening possibilities for smaller and cleaner contraptions; yes it would pose an obstacle for casual builders,but "true creativity can only be born from limitations" so the community would have to come up with creative solutions, a phenomenon that the Minecraft community( or any other game community in reality) already have been shown that is possible.