Pre-Tool stuff
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1 . Create your weapon in 3dmax/gmax (dont forget your frame, I just use frame gun) and use an example weapon as your template, for example the pistol.
2 . open up the gbx model of the pistol and copy out all the markers and put them where you roughly think they would be on your model.(a marker is basically a small box linked to the frame, name your box with a # at the begining, eg #trigger)
3 . Goto your Halo CE root folder and open up the folder called 'Data', inside Data make a folder called 'Weapons', inside Weapons create another folder named 'Gun' and within the 'Gun' folder create these folders - bitmaps, shaders, models, physics, fp and animations. Export your model to your weapons\gun\models folder as gun.jms and then change your materials group name to collision geometry and export it to your physics folder.
4 . The fp folder is for your first person model so within that folder create folders called models, physics and animations, usually the first person model is slightly smaller than the third person model so scale accordingly, (you may have to do alot of messing about to get your first person model in the right place).
5 . Assuming you have moved and scaled your model to the right size and position you should export your model to the fp/models folder, then again in physics (dont forget to rename your material group to collision geometry).
6 . I wont go into the inns and outs of animations so you'll have to do what you can, but I will use the pistols animations for your gun.
Tool stuff
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1 . Open tool and make your bitmaps, gbx models and collision models using the tool commands as below.
2 . tool.exe bitmaps weapons\gun\bitmaps - this will create your bitmaps in a new folder called 'Gun' inside the tags folder
3 . tool.exe model weapons\gun (this may take a few seconds depending on how detailed your gun is and will make your shaders so run it again if it makes your shaders) - this will amke a gbx model of your gun.
4 . tool.exe collision-geometry weapons\gun (this will take no time at all) - this will create your collision model.
5 . Do the above steps again for the first-person model (dont forget its weapons\gun\fp).
Guerilla stuff
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1 . Start guerilla and open the Pistol.weapon tag from tags\weapons\pistol folder, right you will notice that there is an animation graph for pistol and you dont have one!!!, but dont worry coz you dont need it.
2 . Change the Pistol's gbx model to your gun gbx model, do the same for the collision model and delete the animation graph, scroll down to the 'Interface' section and change the Pistols fp gbx model for your gun fp gbx model.
3 . Save the atered Pistol.weapon tag in your 'Gun' folder (in tags not data) as Gun.weapon, you may have to set the bounding radius to get your weapon to not be see-through or walk-through.
4 . Create a new 'item_collection' tag and point it to your gun.weapon tag (dont worry about the weapon respawn because it is goverened in sapien for multiplayer) and then save it in the item collection folder as Gun.item_collection
5 . Open the 'Globals' tag, scroll down to 'weapons list (update)' and add a weapon space, change the tag type to weapon and add your Gun.Item_collection to the weapon list.
6 . Set your shaders bitmaps (you should know how to do this)
Sapien stuff
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1 . All that remains to do is index your model within sapien (little blockhead-man symbol) and place it in your map, you will more than likely have to mess about with your model to get it right which means going through the tool process everytime you need to move/scale your gun, but its worth it because you will have an ADDITIONAL weapon to place in your maps not an overwrite.
I hope this tutorial will help people to get more custom weapons into the game, my next tutorial is on how to import custom vehicles into the game.
by
The Axeman.
www.armyofassassins.com
, dont want floaty guns 
, thx for pointing that out. 
