This MCEdit filter, requested by @Jigarbov on Twitter, clads blocks in the selection box in the block of your choice, leaving an area open. Use it to hide redstone assemblies but still leave tunnels around them for access.

To use, select the area to fill, set the 'base block' to the floor or wall material, then select the block type you want as the sheath. Set the radius to the value of how many blocks to leave space for, and choose whether the tunnel is round or square with the checkbox. Press Filter.