3D Model Basics
Required tools: Paint 3D, usually installed by default on newer versions of Windows.
Step 1: Open Paint 3D
Step 2: Click 'New'
Step 3: Click '3D Shapes' in the top menu. You can alternatively view pre-made models in '3D Library'.
Step 4: Click on '3D View' on the top right of the screen.
this model enables you to change your perspective (by holding mouse right-click by default).
Step 5: Start making!
There are multiple ways to make 3D models. You can start with a base object which should be available in 3D library, or alternatively some basics are available in 3D Shapes.
Doing your own 3D drawing
Use 3D brushes and shapes to make your own drawings
This is the soft edge brush (H) and sharp edge brush (i) used to make a 3D Hi
I added some spheres to make eyes and a tube brush with tapered ends to make a mouth. Then I used the 2D brushes (first option in the top menu) to draw pupils in th eyes.
Beware! Drawing shapes in 3D space doesn't always put them where you want. Hold right click to check the perspective at a different angle before moving on. Move the camera to a side view then select the object and drag it inside your other object to keep them connected.
Modify 3D shapes with brushes:
You can use 2D brushes to draw on 3D shapes to give them details.
Here's a blank face from 3D Paint's 3D Library which I added some details to
Converting 3D models to the correct format:
You can change the format using threejs which is an online editor. Just load (or drag and drop) your 3D model file into threejs then go File -> Export .formatneeded (supported formats for Mixiply are GLB, OBJ and GLTF but not all files of these types will load correctly).