The SM64 Level Importer contains tools to extend the SM64 ROM, import levels, import models, import music sequences, and making many tweaks to the ROM. Start with this tool and continue from there.

• Thread: http://origami64.net/showthread.php?tid=39
• Download: SM64 Level Importer 1.9.3S

Toads Tool 64 is used for adding and manipulating objects and editing some built-in textures.

• Thread: http://origami64.net/showthread.php?tid=38
• Download: Windows Toad's Tool v0.6.2S
• Download: Mac OS X Toad's Tool v0.6.2S

N64Rip is a frontend for Joe's N64 Raw Graphics Tool. It allows you to rip and insert textures into a decompressed (extended) ROM.

• Thread: http://jul.rustedlogic.net/thread.php?id=13199
• Download: http://dl.dropbox.com/u/93572794/Programs/N64Rip.zip
• Source (n64rawgfx): https://github.com/Octocontrabass/n64rawgfx

The Skybox Importer allows you to easily view and change the level skyboxes.

• Thread: http://www.smwcentral.net/?p=viewthread&t=77986
• Download: Skybox Importer v1.11
• Source: https://github.com/DavidSM64/SM64SkyboxImporter

LemAsm is a hex editor with built-in disassembler and assembler. You can use it to make quick asm changes in N64 ROMs. Also contains an image viewer.

• Homepage: http://nemu.emuunlim.org/lemasm.php
• Download: LemAsm v0.1

CajeASM is a MIPS R4300i assembler that supports a highly configurable assembly and data input and injecting directly into a ROM.

• Thread: http://origami64.net/showthread.php?tid=30
• Download: CajeASM v7.24
• Source: https://github.com/Tarek701/CajeASM