Just an idea here.
In the Halo 3 era before Sandbox was released, Forgehub developed a neat and detailed wishlist for everything they wanted to see in the new Forge system. This list included lighting effects, balls that kill you when they make contact, and (I believe) golf clubs and holes. Since the thread Forgehub made was met with so much sucsess despite being made only 2 weeks or so before the release of Sandbox, something similar could find much sucsess if it were made for Halo 4 forge.
The way it would work is an admin of the community would make an official pinned thread in which all members of the community can post their thoughts on what they want in Halo 4 forge. Of course making sure not to be pushy or hurtful. Then all the comments would be sifted through and any that were reasonable and feasible would be put in a master-list and then emailed to the correct people at bungie... yadda yadda...