Simple Burglar Alarm setup. requiring help plz. :)

hey, i am making a project which is a model room containing a burglar alarm system, i need to find out many ways of doing this off the 1 micro controller (like a 18X or 28X etc)...also i would like to include if possible a sensor (like in the pillars outside the room) that senses some1 coming and automatically rings a chime (door bell) to alert that some1 is coming,

thx heaps in advance, and every commment will help, so plz dont hold bak.

https://electro-tech-online.com/viewtopic.php?t=12983

This will give a beep to let you know someone's coming.

Radio Shack (and probably many others) sell many kinds of sensors for this purpose.

thanx zach...and where in my post did i mention i didnt know where to buy parts, i just need to know how to go about making this project mainly off the one project and layout etc.