I've made one today for for de_cache (Attachment). It is for under 10 players. Mid (+ramp) and Main A only.
Regarding on how to do one yourself... it is time consuming job but the more of us do it, faster we'll have restrictions for all maps.
Tutorial:
- bot kick (or bot_kick)
- mp_freezetime 0
- bind / "mp_restartround 1"
- cl_showpos 1
Now, prepare fresh "<mapname>.ini" (or copy from existing one), switch to game and go to the place you want to restrict (put the fence). Note the values from the top left corner of the game (activated by cl_showpos) and copy them to the value in ini file and save. It'll take some time to get really efficient at it...
Now, pres that "/" button to restart the round so the props can reload. Go to the place you placed the fence and tweak values if needed.