[NOTE: These tutorials are out-of-date, as they are for meshmixer02, circa early 2010. However, the hotkeys have been updated for meshmixer07! ]
meshmixer has a pretty spartan interface, so there isn't a lot to learn. Tutorials will go up as I get to them. Here is what I've got so far:
Selection Tools
Drag and Drop Tool
Filling Tool
Smoothing Tool
Making Your Own Parts
These video tutorials might also be useful:
Tutorial Video 1: Basic Drag & Drop
You might also want to check out the Frequently Asked Questions.
Many of the operations in meshmixer can be accessed via hotkey. Here is a short list of the available hotkeys (updated for mm05!)
[Basic Controls]
Alt+LeftMouse: tumble camera around object (turntable mode)
Alt+MiddleMouse: pan camera
Alt+Shift+LeftMouse: pan camera
Alt+RightMouse: zoom camera
Alt+Ctrl+LeftMouse: zoom camera
f: import new mesh (mesh)
e: Export current mesh
Ctrl+S: Save current .mix file / save as new .mix
Ctrl+O: Open existing .mix file
Ctrl+Z: Undo
Ctrl+Y: Redo
Alt+Left: Undo
Alt+Right: Redo
ESC: cancel current operation (selection, cut/fill, drop)
a: Accept current action
s: switch to Selection tool
w: toggle Wireframe
b: draw Boundary edges (useful for debugging)
(: previous view
): next view
[Selection Tool]
LeftMouse (+drag): add to selection (click, or drag to paint)
Shift+LeftMouse: remove from selection (click, or drag to paint)
RightMouse+drag: grow/shrink selection
mouse wheel: brush size
[Volume Brush Tool]
LeftMouse: apply primary brush
Shift+LeftMouse: apply secondary brush
Ctrl+LeftMouse: invert brush (only certain brushes)
mouse wheel: brush size
[: decrease brush size
]: increase brush size
[Smoothing Tool]
left/right arrows: increase/decrease Scale parameterup/down arrows: increase/decrease Smooth parameter
mouse wheel: increase/decrease Smooth parameter