Unity3D, ProBuilder, and Mixamo.com - Building Mario 3D Model within Unity and Animating in Mixamo

In this tutorial, I will cover using ProBuilder (FREE 3D modeling) within Unity 3D to build out a simple Mario game character and then animate the character using Mixamo.com and importing back into Unity. ► Download Unity at https://unity.com ► Visit Kenney.nl for great game assets at https://ke

This guide walks the full pipeline of taking a homemade 3D character from a blockout in Unity's ProBuilder all the way to playable animations, using Mixamo's free auto-rigger and motion library in between. The example builds a simple Mario-style figure, but the workflow applies to any low-poly character.

Bring in a reference and set up ProBuilder

Import your concept art into a sprites folder and set its Texture Type to Sprite (2D and UI), then Apply, so you can stand the reference in the scene and model against it. ProBuilder ships with Unity — if it isn't already in your project, grab it from the Package Manager. Its window toggles between icon and text mode via the three-dot menu, whichever you prefer.

Model with the four core tools

Add a shape (a cube is fine) and learn the four selection modes at the top of the editor: object move, vertex, edge, and face. Each can be moved, rotated, or scaled to deform the mesh. The key technique is holding Shift while dragging, rotating, or scaling a face — that extrudes a new segment, which is how you grow limbs and details. Keep it simple and build the character in a T-pose, the recommended stance for rigging. ProBuilder's vertex paint tool lets you color faces directly for quick flat shading.

Export an FBX

Rigging needs an FBX, which requires the FBX Exporter package (install from Package Manager if missing). Rename the object meaningfully, then use GameObject > Export To FBX. Save into your assets, leave the transform as-is, but change the export format from ASCII to Binary before exporting.

Auto-rig in Mixamo

At mixamo.com choose Upload Character and drag in the FBX. Rotate it on the Y axis so it faces forward, then place the joint markers — chin, wrists, elbows, knees, and groin — and uncheck symmetry if your model is slightly uneven so you can position each side independently. For the Skeleton LOD, pick No Fingers when the hands are solid fists, which keeps the bone count low. Mixamo then rigs the character automatically.

Download animations and wire the Animator

Preview Mixamo's animation library on your rigged character. Download an idle as FBX for Unity With Skin and keyframe reduction; download a run as In Place (so it doesn't drift off-screen) Without Skin since the mesh already came down with the idle. Back in Unity, duplicate the clips out of the imported FBX files into your animation folder, create an Animator Controller (e.g. mario anims), and assign it to the character's Animator. Drop the idle in first as the default state, add the run, and create transitions between them — pressing play confirms the character now idles and runs from your own model.