I have hand dug a "bomb shelter"/ multi-use "room" under my tool shop (outdoor building). This has taken me about three years, and hundreds of buckets of dirt up the ladder! It's 12 feet deep, and currently, 6 ft high, by 5 ft wide by 5 ft wide. In the middle of the floor of the tool shop, I have cut out a piece of the floor which is on hinges, and can be opened and closed as needed. A carpet covers this when not necessary to access the shelter. Nobody knows about it but me at this point. About a foot down below that, I have created a "false" top to the opening, which is just a sheet of plywood covered with dirt, which makes it look as if it is just the ground underneath the building. Currently, I am manually sliding the plywood off of the opening, which reveals the ladder down, and lights and door into the "room". What I need help with is motorizing this process. I would like to open the hinged plywood floor (manually), see just the "ground", and then somehow, activate a motor to slide the plywood off of the opening. (The way it is now, if anyone does discover the hinged opening under the carpet, all they will see if they open it is what just looks like the ground under the building.) The "false" ground/ door to the shelter opens about 40 inches, which is room enough for anyone to get onto the ladder and go down. I have explored various options, such as linear actuators, motors and pulley's, etc, but I'm stuck. I plan to make a track for the plywood to slide back and forth in. I need to be able to slide open the "door" from the top, while up in the building (motorized), and then be able to close it when down in the "shelter". Do they make actuators with that length of throw, and if so, aren't they very expensive? I've also explored the idea of mounting a nut on the board, using threaded rod attached to a motor, and somehow open it that way. I'm not sure how much the plywood weighs with the dirt on it. Thanks so much for any help and ideas. I plan to submit pictures as I can. P.S.-Not that important just yet, but once I have the motorized opening figured out, I want to either switch it on with possibly entering a code on a keypad, or somehow a "hidden" switch, like what they did in "Batman"(TV Series), or use something in the shop that looks like one thing, but would actually trigger the motor. Thanks!!