Motor Lock and towers

First, make this using motors, and place a cylinder in between. (you can make it as high as you want) 

Now, make this the settings on the motors.

This is done so the motor lock can work.

That's a motor lock tower complete. you can add TNT in the gaps,  with 0 for everything in the setting to allow it not to lock straight away, it should look something like this when loaded in.

you can put anything on these motors as long as it doesn't touch the bottom and top motor at the same time, motor lock can also be done sideways, upside-down, vertical, anyway possible.

SINGLE MOTOR LOCK-

Simply do this.

ensure it has the same controls as the tower, BOOM! its done. you can only connect to the top and sides (SIDES: as long as it doesn't touch the flat and long bit at the same time)