Update 2019-10-17 Static Timed Weapons now function properly from the second round on in round based games. In order to fix your map you must replace the control brains with the new Static Weapons Brains prefab linked below.

Update 2018-03-26
Added:
180 second railgun
120 second Plasma Caster, FRG, Railgun, Hydra Launcher, Binary Rifle
90 second Shotgun, Needler, Hammer, Light Rifle, Sentinel Beam, DMR, Scattershot

Scripts programmed by Yumudas Beegbut.

Static Timed Weapons allows you to spawn your Power Weapons and Powerups at EXACT 2 or 3 minute intervals. You can see this weapon spawning system in the Halo 3 Classic Playlist.

This system for delivering power weapons evolved from the 'Drop Spawn' system found on Halo 3 MLG competitive maps. The general idea is that power weapons which arrive on a timer allow for consistent and predictable Map, Weapon, & Powerup control.

Power Weapons will spawn at EXACTLY the correct time. If not picked up they will despawn about 5 seconds before the next one shows up (to prevent ammo doubling). If picked up and dropped, or the player dies while carrying, they will 'clean up' in about 20 seconds.

Script compatibility: This script uses Global Victor, Whiskey and X-ray Numbers. Each weapon has the Sierra Label.

Prefabs

The main Prefab is required for all installations. This contains 4 Script Brains which should be placed first. Please do not alter or ungroup this set. They are setup to NOT fire in Forge Mode.

Static Weapon Brains

Powerups

H3powerup by NOKYARD, on Flickr

H5Powerup by NOKYARD, on Flickr

There are 5 Powerup Prefabs available: These feature a script which removes the activation animation (slap on chest).
120 Active Camo
120 Overshield
180 Active Camo
180 Overshield
180 Speed Boost (Not a Classic Powerup but i included it anyway)

Placing a Powerup

The 'ball' is actually a FX: Beam: Plasma 8X16 so the lower part of the beam must be set into the floor to make the Beam appear as a ball (the FX: Glows were unsuitable for this application). There is a Cortana Doll attached to each Powerup Prefab to assist with precise placement. Lower the doll until Cortana's feet just rest on the floor. The Cortana Doll has a 'forge:include' Label so there is no need to delete the Doll. It's best to keep the prefab intact in so you may reposition at a later time.

ActiveCamo by NOKYARD, on Flickr

Powerup Prefabs are self contained and require no hills like the Weapon Prefabs. There are no limits as to how many, or of which type, you can place.

Why Green? The Overshield in Halo 3 was a red orb but we decided to change it to green for 3 reasons; In all following games red Powerups are attributed to Damage Boost, your Shields emit a green glow while the Overshield is active, and the activation sequence looks bad ass.

Power Weapons

H3120 Sniper by NOKYARD, on Flickr

H5120Sniper by NOKYARD, on Flickr

There are 15 Power Weapon Prefabs available. They are assembled in groups to keep the number of files down. Unless otherwise noted all weapons are the [standard] variant. The 'b' sets are explained further down.

120 Relic Sword (Covie Weapon Holder)
150 Relic Sword (Covie Weapon Holder)
180 Relic Sword (Covie Weapon Holder)
90 Weapons (Shotgun, Needler, Hammer, Light Rifle, Sentinel Beam, DMR, Scattershot)
90b Weapons (same as above)
120 Snipe Rockets (Sniper, SPNKr)
120b SnipeRockets (same as above)
120 Weapons (Needler, Shotgun, Spartan Laser, Gravity Hammer, Rocket Turret [ONI Detached], Plasma Caster, FRG, Railgun, Hydra Launcher, Binary Rifle)
120b Weapons (same as above)
150 Snipe Sword (Snipe-Narrows, Halo 5 Sword-Blackout, Halo 2 Beam, Binary Rifle)
150b Snipe Sword (same as above)
180 Snipe Rockets (Sniper, SPNKr)
180b SnipeRockets (same as above)
180 Weapons (Halo 5 Sword, Shotgun, Beam Rifle Halo 2, Gravity Hammer, Rocket Turret [ONI Detached], Railgun)
180b Weapons (same as above)

Placing Power Weapons

For reference:
Team 6 (Purple Hill) is for the 90 second timing
Team 6 (Magenta Hill) = 120 secons
Team 7 (Gold Hill) = 150 seconds
Team 8 (Cyan Hill) = 180 seconds
You can not mix timings (120 Sniper in a 180 Hill)

Select the Prefab you wish to place.
SelectPrefab by NOKYARD, on Flickr

Drop Prefab by NOKYARD, on Flickr

There will be extra weapons you don't need so ungroup the set and delete the unneeded weapons now.

Delete Extra by NOKYARD, on Flickr

The 'Safe Hill' is very important. While the weapon is within this hill it will not despawn. If it leaves the hill, or is picked up and dropped outside of the hill, it will despawn in 20 seconds. Adjust the hill to suit the 'safe' area for your weapon placement keeping in mind that Grenades will knock the weapon from it's spawn position.

AdjustHill by NOKYARD, on Flickr

Once placed set the Boundary Show = Off to hide the hill.

BoubdaryHillOff by NOKYARD, on Flickr

***NEW as of Nov 2018***

IMPORTANT - The old prefabs contained 4 of each weapon. In order to simplify the process prefabs now contain one of each weapon. Duplicate your weapon 3 more times so you will have 4 of the weapon.

PositionMixed by NOKYARD, on Flickr

Navigate to Object Properties/Position and press D-pad/Left on each of the 3 Positions (X, Y, & Z) so there is a number in each. This will ensure all 4 weapons overlap to make placement easier.

PositionSame by NOKYARD, on Flickr

Place the weapons (they should remain Phased for now).

BadHill by NOKYARD, on Flickr

Each weapon has a small visible hill. This (very important) hill signals to the included scripts that the weapon is being held. You MUST be sure that players are not able to intersect this hill when the weapon is in position.

HillIntersect by NOKYARD, on Flickr

If a player intersects with this hill (in the chest area or helmet) the weapon will despawn after 20 seconds even if the weapon is not grabbed. Make sure to place the weapon so the hill is out of the way.

NormalHillOff by NOKYARD, on Flickr

Set the weapons to Normal Physics and set Boundary Show = Off.

NormalHillOff by NOKYARD, on Flickr

The weapon should look like this when complete.

Success by NOKYARD, on Flickr

Placing more than 1 set of the same weapon

'b' Sets

The 'b' sets are for cases where your map requires two sets of the same weapon in two different locations. For example the 2 Sniper locations on The Pit would require you to place '120 Snipe Rockets' for Red side, and '120b Snipe Rockets' for Blue side.

The scripts use Spawn Order to keep track of individual weapon pools. For example all 4 of the 180 Rockets use Spawn Order = 1. The Spawn Order in the 'b' sets are 10 higher than the same weapon in the regular prefab.

Placing more than 2 sets of the same weapon

Each set of 4 weapons in the Prefabs uses a unique Spawn Order so the script brains can differentiate between weapon pools. It is important that each weapon pool on your map feature a unique Spawn Order.

The scripts do not allow for the same weapon placement to be set more than once so DO NOT Copy/Paste prefabs.

If your map requires 4 Sniper locations it is simple to adjust the scripts to make extra prefabs.

Simply Place 2 more installations of '120b Snipe Rockets' as per above. Then select all the Snipers in set 3 and add 10 to the Spawn Order of each weapon in that set. Select all the Snipers in set 4 and add 20 to the Spawn Order.

As long as each individual weapon location features a different Spawn Order your weapons should function normally. The reason you must use 10 is so there is no overlap with the other weapon placements on your map. Do not go above Order 53.

These are the reserved Spawn Orders. You may choose any Spawn Order not listed here as the Spawn Order for your extra weapon pools.
[spoiler]
Spawn Order reservations
Team 5 (Purple Hill) = 90 seconds
Team 6 (Magenta Hill) = 120 seconds
Team 7 (Gold Hill) = 150 seconds
Team 8 (Cyan Hill) = 180 seconds
All powerups are Spawn Order 59
120 Relic Sword 8 (Covie Weapon Holder)
150 Relic Sword 18 (Covie Weapon Holder)
180 Relic Sword 28 (Covie Weapon Holder)
90 Weapons (Shotgun 7, Needler 9, Hammer 5, Light Rifle 8, Sentinel Beam 21, DMR 22, Scattershot 23)
90b Weapons (Shotgun 17, Needler 19, Hammer 15, Light Rifle 18, Sentinel Beam 31, DMR 32, Scattershot 33)
120 Snipe Rockets (Sniper 2, SPNKr 1, H2 Beam 47, Scattershot 49)
120b SnipeRockets (Sniper 12, SPNKr 11, H2 Beam 48, Scattershot 50)
120 Weapons (Needler 9, Shotgun 7, Spartan Laser 10, Gravity Hammer 5, Rocket Turret [ONI Detached] 4 , Plasma Caster 24, FRG 25, Railgun 26, Hydra Launcher 27, Binary Rifle 28)
120b Weapons (Needler 19, Shotgun 17, Spartan Laser 20, Gravity Hammer 15, Rocket Turret [ONI Detached] 14, Plasma Caster 34, FRG 35, Railgun 36, Hydra Launcher 37, Binary Rifle 38)
150 Snipe Sword (Snipe-Narrows 2, Sword-Blackout 3, H2 Beam 41, Binary 43, Scattershot 45)
150b Snipe Sword (Snipe-Narrows 12, Sword-Blackout 13, H2 Beam 42, Binary 44, Scattershot 46)
180 Snipe Rockets (Sniper 2, SPNKr 1)
180b SnipeRockets (Sniper 12, SPNKr 11)
180 Weapons (Sword 3, Shotgun 7, Beam Rifle H2 6, Gravity Hammer 5, Rocket Turret [ONI Detached] 4, Railgun 29, Plasma Caster 51)
180b Weapons (Sword 13, Shotgun 17, Beam Rifle Halo 2, Gravity Hammer 15, Rocket Turret [ONI Detached] 14, Railgun 39, Plasma Caster 52)
[/spoiler]

Run Time Maximum

RunTimeMaximum4 by NOKYARD, on Flickr

Halo 3 had a unique feature called Run Time Maximum which allowed you to control the total number of a given weapon on your map during the course of a game. If the Sniper was set to 4, and 4 players were holding a Sniper, a 5th Sniper would not spawn. This (i assume) was to prevent everyone from holding a Sniper. It's an unlikely event but our script allows for exactly this feature.

If your map contains 2 of the same power weapon (like the 2 Snipers on The Pit) you may wish to limit the total number of weapons available to players to a maximum of 4. To accomplish this you place the A prefab in one location, and place the B prefab in the other location. Duplicate the weapon in each location so there are 2 of the weapons per location, for a total of 4.

Duplicate 2 per side by NOKYARD, on Flickr

Custom Weapon Sets

I will be posting the instructions for making your own Prefabs here in a few days. Until then simply copy the scripts in the existing weapons, keeping in mind that each weapon pool on the map must have a unique Spawn Order.