Something like EnderIO conduits, but simpler: just a block which can transmit pretty much anything GC might need. Most importantly, power and oxygen. Maybe fuel, too. You would craft it by putting a fuel pipe, an oxygen pipe and a wire into the middle row of the crafting grid, and then 3 metal plates in the top and in the bottom rows. The result would be a sealable block which can be placed into walls or floors to transmit these things.