Super Mario Maker and its sequel are terrific games that let fans create and share their own Mario levels with ease. But it was a bit of a disappointment that Nintendo only factored in the 2D Mario games. None of the plumber's 3D incarnations have made it to a Mario Maker title to date. So thank goodness for modders.
A pair of modders named Arthurtilly and Rovertronic have released an open-source Super Mario 64 mod that aims to make it a cinch for players to create and share their own levels. You'll need your own (legally obtained) Mario 64 game file and a separate piece of software to infuse the mod into it. It's even possible to use Mario Builder 64 on a Nintendo 64 if you have a supported flashcart.
You'll have more than 100 parts to build your levels with. The creation tool includes some custom parts from a previous mod, so you have extras like permanent powerups at your disposal. To share your creations and find those made by others, the recommended places to look are a website for Mario level modders and Rovertronic's Discord server.
It'll be interesting to see if ridiculous 3D kaizo-style levels start popping up, while the mod could allow speedrunners to create custom training grounds where they can practice strategies. Personally, I'm hoping for creators to build levels that rely on half-A presses to beat.