Most ships could use a docking tube. It makes docking at spawn or your friends base a tad bit easier.. If at all possible in your ship designs, work in a docking tube or two: you'll be glad you did. Docking tubes are a good way for vessels to connect together in space. Large vessels that cannot fit into the hangar entrances at spawn must have docking tubes if they wish to connect to the space station.
a docking tube
The wool has to be wool, though it can be any color. Now line the outside of your door with stone buttons. You'll need a sign on the inside of your ship on a block next to it. To make that sign, put [dockingtube] on the first line and right click it. This docking tube attatchment should be built into the side of your ship. To dock your ship, line the docking tube door on your ship up with another docking tube door. That second door could be on a space station, second starship, docking tower, or anything. When you have the docking tube doors lined up properly, right click the docking tube sign. If it is lined up properly, a tunnel of glass will extend to connect the two docking tube doors, and you can walk through it. If you want to disconnect them, right click the sign again.
Properly aligned docking tubes.
Connected docking tubes.