You can create all sorts of buttons, activated by triggers, or simply by touching or using it. Anyway on to how to make your own but

Buttons for doors

The most obvious button you might need is a button to open up a door, easy enough to do really. After you have created your door, give it a name, say "mrdoor". You dont need to worry about the other door entities, its just like any other normal door.

Now one thing you might want to know is that there are button textures, you dont have to use them, but some are good, if you want your button off, then place the "off button texture" on your button, rather than the "on texture", for instance, there's one button texture with a green light and one with a red light, so if you want the button to start off, then put on the button use the red texture. soon as you press it it will go green in game as it has been turned on,

Anyway make yourself a little button to go with that door. Tie it to the entity func_button now you need to sort out the following properties

Name: just give it a name i.e. button1
target: what you want the button to open/close, so ours would be "mrdoor" as thats the doors name
fx_amount 255

There are other things to set as well, such as the sound of the button, and other self explanatory things, so change them as you see fit.

Now in the "flags" section of your func_button, tick "dont move", otherwise your button will move and most of the time you dont want it to actually move. If you want people to just touch activate it then tick "touch activates" if not just leave it and people will have to "use" it to activate it. You can also tick the box for sparks if you want it to have sparks.

Its that easy to do, now you wont want people moving through the door without pressing the button most times, so make sure in your func_door no flags are ticked. You can play with all the settings to see what happens if you like, say if you need it open to start with, then tick starts open for the door. Its all obvious what to tick.

Triggering lasers

Someone recently mailed me asking how to trigger off a func_laser, I made him a quick map and sent it to him, he never replied back like, oh well.

Anyway its quite simple. First put in a env_laser and set the following properties:

Name: call it "laser" (without the quotes)
target of laser: this is what your laser hits, give it the name of "target1"

You can leave all the rest to the default settings, its all obvious what changes what, I mean come on I dont have to tell you beam colour changes the beam colour do I! :) also dont tick any of the flags.

Moving on, we now need a target for the laser, so select the entity info_target and call it "target1" thats all the properties that you need to change in that entity, as there aren't anymore.

Now we have a laser, we need a button, make your object for the button, and tie it to a func_button, just call it button1. fx_amount 255, targeted object "laser" and tick the flag "dont move". Thats your essential stuff up, you can mess about with the other settings, but basically just remember make a laser, give it a name, and then on your button target the laser.