Transparent Scenery Glitch

The Translucent Scenery Glitch is a glitch present in Halo 3 's forge mode on the level Foundry, in which the spawned item will appear translucent when held.

Walkthrough
To trigger the glitch, position yourself (the monitor) along the lower ceiling, where the teams would spawn on Team Slayer, and face straight ahead so that your line of sight is more or less parallel to the lowered ceiling and you are facing in the direction of the team spawn points. Go to the scenery menu and select an item (this works particularly well with stairs, but some items will not work at all). If done correctly, the spawned item should appear in the center of the map closest to the side the forging player is on. The player who forges the item will be unable to see it unless he exits the game and then views it in Theater mode, so this works much more effectively if there is another player working as a spectator. Letting go of the object will remove this effect, and sometimes launch the item a short distance across the map.

Trivia

 * If the spectating player moves into the forged item, it will disappear. It does not matter if the second player is in forge mode or not.
 * In some situations, the transparent item will appear in two locations at once.
 * If the spectator switches to monitor mode and places his reticule on a transparent scenery item, he will see both the normal reticle and the one telling him the item cannot be picked up.
 * When viewing in theater mode, pausing the video will cause one of the transparent items to become solid and the other to disappear. This is because each frame registers the item in either one location or the other, and never in both places at once.

Explanation
The reason for the phenomenon is the fact that the physics engine encoded into the Halo disk can not decide where the item should be placed, so it "jumps" between two spots, and is therefore only there half the time, explaining both why the box sometimes appears in two places and why the object being forged appears transparent.