Introduction
If you are not comfortable with constructing entities in your map editor this is NOT the one to start with.  However, this is a much "simpler" version of an elevator than the 5 floor elevator described by Cisum at the 6th floor (look under resources/tutorials).  The point of this elevator is to use only two stops and  to keep gameplay fast by NOT using a visible keyboard interface - note that it does pass multiple floors. This particular elevator has buttons (black triangles) which will call the elevator to the top or bottom floors. To make things a lot easier on you here is the mapfile for this tutorial (including a complied .bsp).  If you do not know where these go, well...

Step 1 - do the brushwork (origin brush too!)

• make your elevator or whatever thing you want to move between two points.  Below is the elevator in the attached mapfile. (see figure 1)
• make sure you provide an origin for the object - you can do this manually as a key/value pair but it is more intuitive to use a brush - in the picture below the orange box in the corner is the origin (flush with the bottom and outside edges of the elevator) - it is a 16x16x16 brush covered with common/origin texture .
• once you have it looking the way you want select every brush that will make the moving object...

Step 2 - make it a func_ut_train and set the key/value pairs

• with all the brushes selected bring down the entities menu (right click in Radiant) and select func_ut_train.
• set the keys/value pairs for the train as per the diagram below (figure 2)
• note: that the func_ut_train targets one of the path_ut_stops in step 3 - allowing you to actually draw the catapult where ever you like - this is useful when you include complicated texturing which (if I remember correctly), like rotating doors, aligns with the world origin (x-0; y-0; z-0) - in such cases it is a good idea to do the final texturing with your elevator's origin exactly overlapping the world origin

Step 3 - tell it where to go - path_ut_stops

• insert two path_ut_stops - that's all, no waypoint path_ut_stops needed!
• in gtkradiant for example right click anywhere on the worksurface window and select path_ut_stop
• remember that the origin brush is what aligns with these path_ut_stop entities when it moves - thus, in this case you will want the path_ut_stops exactly aligned in the vertical (z-axis)
• set the key/value pairs as per the diagram - this particular one is for the TOP floor stop - you will need to make key/value pairs for the BOTTOM as well - see figure 6 below.

figure 3

figure 4

Step 4 - connect the elevator entity to the path_ut_stops - func_keyboard_interface

• the func_keyboard_interface is what connects everything up - the source of many errors in making func_ut_trains
• make a brush, cover it with common/nodraw (purple) on all sides (see figure 1)
• set the keys as in the diagram below (figure 5)
• note that display is set to 0 so you do not actually see the interface - in order to make it go, you simple press the use key in UT or you press one of the call buttons (see below)

Step 5 - call buttons - trigger_multiple; target_speaker; target_relay

• you don't have to include call buttons but players will want them
• essentially you create an invisible trigger_multiple that surrounds a visible brush that will be your visible call button
• the trigger_multiple targets a relay (target_relay) as well as a sound (target_speaker) - of course it would be simpler to have the trigger_multiple target the path_ut_stop and the target_speaker at the same time, but for some reason this messes up the ut_train (hence the need for the relay)
• note: a func_button is not used here due to problems with setting the push_sound key (seem to not work) or disabling the default button sound

NOTES

• to use the elevator in the game you either a) get close to it and press the use key (this includes when you are ON it) or b) press the call button (this will NOT work if the elevator is already at your stop - e.g. pressing the top button when the elevator is at the top will only make a nice beep sound but the elevator will not move
• this simple train can be transformed into various interesting in-game moving objects - for tutorials on more complex uses of func_ut_trains (e.g. the object rotates as it moves) see the tutorials on making a helicopter and an elevator that stops at several floors at the 6th Floor
• to see how to make a catapult with a func_ut_train go here
• for further help with func_ut_trains please visit the UT level design forum