TTT style C4

Having been playing Trouble in Terrorist Town for a good few days, I want to see something similar or the same as the C4 in that gamemode. The idea is the player types in a code on a GUI (or if possible on this request, the actual entity), sets the timer and clicks “Arm” to begin countdown.

To disarm the code must be typed in again. When a correct number in one of the number slots is typed in but the rest are wrong, the correct number(s) are displayed to make it a bit easier to disarm. When an incorrect code a fraction of the time is slashed off so random bruteforcing won’t get very far.

There should also be a defuser SWEP. I’m not sure how TTT’s defuser works but I’m thinking either an automatic CSS style disarmer or it should reduce the penalties or make it easier to disarm the bomb.
Oh yeah, the countdown should be displayed on the LCD screen of the C4 model. Perhaps one of these models could be used: