A dedicated "visualizer" entity

[Pinsplash]

You spend minutes putting down those prop entities to make sure your map's scale is correct, or compiling it and placing sentries manually to see if they can cover a room. "There must be a slightly easier way," you say. Now there is!

Spoiler

@PointClass base(Angles) studioprop() sphere(radius) line(255 255 0, targetname, linestart, targetname, lineend) = tf_visualizer : "This is a fake entity, which acts as a visualizer primarily meant to help with the scale of the map."
[
   targetname(target_source) : "Name" : : "The name that other entities refer to this entity by."
   model(choices) : "Model" : "models/player/heavy.mdl" : "Tip: in the Model tab, set Sequence to stand_PRIMARY or crouch_PRIMARY (or SECONDARY for spy) to see what the player may actually look like while standing or crouching. Use 'refpose' for sentries." =
   [
     "models/editor/axis_helper_thick.mdl" : "None"
     "models/player/scout.mdl" : "Scout"
     "models/player/soldier.mdl" : "Soldier"
     "models/player/pyro.mdl" : "Pyro"
     "models/player/demo.mdl" : "Demo"
     "models/player/heavy.mdl" : "Heavy"
     "models/player/engineer.mdl" : "Engineer"
     "models/player/medic.mdl" : "Medic"
     "models/player/sniper.mdl" : "Sniper"
     "models/player/spy.mdl" : "Spy"
     "models/buildables/sentry1.mdl" : "Sentry (lvl 1)"
     "models/buildables/sentry2.mdl" : "Sentry (lvl 2)"
     "models/buildables/sentry3.mdl" : "Sentry (lvl 3)"
     "models/buildables/dispenser_lvl3_light.mdl" : "Dispenser"
     "models/buildables/teleporter_light.mdl" : "Teleporter (add 36 units for particle height)"
   ]
   radius(choices) : "Radius" : 0 : "Note: Distances do not take player/building hulls into account." =
   [
     160 : "Typical explosion radius (rocket, grenade, sticky, sentry rocket)"
     575 : "Max airblast distance"
     1100 : "Sentry gun 'eyesight'"
     1120 : "Demo shield charge distance (usual)"
     1500 : "Demo shield charge distance (claidheamh mor)"
     1440 : "Demo max grenade distance (stock)"
     2180 : "Demo max grenade distance (loch n load)"
   ]
   linestart(target_destination) : "Line Start" : "" : "Draw a line from this entity to Line End. Do not use this for checking sentry vision."
   lineend(target_destination) : "Line End" : "" : "Draw a line from Line Start to this entity."
]

This FGD code will give Hammer a fake entity called tf_visualizer. It shows the most common TF2 models, all in a dropdown, shows a few distances, like the sentry gun's max range, and it can draw lines! (YEAH, BABY!) Place the code above into any FGD Hammer reads from, and you're set.