I want to put a keypad and a 2x16 character LCD in this door to control the board.the box must be water resist. I want to change or modify this door so that it looks beautiful. currently I want to design a Capacitive touch keypad but what is next or how can I put it in the box. My question is what kind of keypad do you suggests and how much is the cost? I can even change the box if a better suggestion.
Let's assume that the box is fully waterproof, I would still recommend using a box as the one Michel suggested. The main reason for this is the transparant cover. You really don't want to drill holes in the cover and try to make everything water proof so what is easier then mounting everything inside. With the transparant cover you can easily read the lcd and you can mount capacitive buttons on the inside of the lid. Example in figure below. *image taken from Source image
regarding the touch buttons themselves, the capacitive touch buttons are quite easy to do, they are being used extensively for this purpose. I would suggest reading the "TI slaa576a" Design Document Design Document the document describes the theory of operation and the ways you can design your buttons, which materials you can use and so on. As far as IC's go there are lots of options to choose from, fully assembled breakout board based on the "Atmel AT42QT1070" or the "microchip MTCH101" or a lot more options. Pricing and cost will be determined by your final solution but should definitely not break the bank. The IC's I listed are both available for less then 1 euro.
Are you sure your box is waterproof. I would think more like this enclosure box. You have to find one that fits your size better (this one is too small, just as example). It has a rubber inlay, and more important, no holes through the box.
About the LCD, just make sure you glue it very good so it is waterproof. Typically, 1602 and 2004 displays are used, unless you want a graphic screen (OLED maybe).
About the keypad, you cannot use probably ones with feedback/'moving' keys, so a 4x4 keypad might do. Costs: < 1 euro/$.
If you can do a bit of micro-controller programming, there is a very neat way to do that with capacitive touch sensing.
You can sense the touch trough plastic, metals like aluminium, glass, keeping the electronic safe from water damage and making the design very simple.
If you don't want to program or do electronics, you can use an evaluation kit which is ready to use.