This post may contain an affiliate link that helps support GBFans.com when you make a purchase at no additional cost to you.The easiest and cheapest way that i found is to get 2 cheap 5g servos off ebay, a durable spst switch that can hide in the trap bellows, and the $17 Spark Fun servo trigger. it only does 90 degrees but you cant beat it and it looks fine. just give it 5v and youre good to go. all you need is VERY basic soldering skills.
EDIT: more info
Doors are easy and super cheap to do
The control board is from spark fun
https://www.sparkfun.com/products/13118 its only seventeen dollars! all you do is connect both servos together solder the servo wires, pedal switch and power supply to the board and youre done. super easy. no programming. anyone can do it and its really cheap. the only catch is, that is as fast as the doors open and close (kinda slow) and it only does 90 degrees of travel instead of the 120 or so that the movie traps do. but for how easy and cheap it is, i think its fine.
i also wired in a hidden switch to cut power to this board to keep the servos quiet when its hanging on your belt. servos like to make a lot of noise all the time as you can tell from the video.
here's some cheap servos:
https://www.ebay.com/itm/Tiny-Mini-5g-r ... SwbYZXY1Lv youll need SPST/SPDT switch that is small enough to hide in the pedal bellows, but is also heavy duty because youll be stepping on it with a lot of force. this switch fit perfectly and the pedal base only needed a little dremeling to get it to work
https://www.ebay.com/itm/151915471015 its even SPDT so you can use the other contact for something else if you ever wanted to.
i used a 12v power supply and a 5v voltage regulator to power the servo board which needs 5v.
like this:
https://www.ebay.com/itm/Car-DC-12V-to- ... Swr8xZ8FjV the 12v battery is rechargeable and never leaves the trap
http://www.batteryspace.com/nimhbattery ... robot.aspx 2200 mAh is pretty decent and should last a whole day of use