I made a mod called Portal-Mod (aka Portal Gun)

[Al4n]

This mod will allow you to have the fully working portal gun with portals and an option to clean them, its first person but still has the same mario movement, so you can finish the game pretty much the same way but with portals.

 

[SuperStar!]

Its cool mod I saw the mod on gamebanana and it has the portal gun which is cooler then the other portal mod peachypeach made

 

[Al4n]

also, yeah here's the mod: Portal Gun Mod for Super Mario 64 Co-op (EX & DX) | sm64coop Mods if somebody wants to play it before i post it on sm64coopdx website