Revolve can spin about a line you drew in the sketch. Set Axis to "A line of the sketch" and pick the line — construction lines included, which is what the dashed centreline of a lathe profile is

The axis follows that line when you move it, so dragging the centreline moves the bore with it.

Bones from the shape of your parts. Right-click a part and pick Make a bone from this part: it measures the part and adds a bone down its longest axis, already pinned to it.

The same from the feature tree — right-click the feature that built the parts and get one bone per part it made, so a patterned row of eight fingers is one click instead of eight.

The bone takes the part's name, and a part is named after the feature that made it. Call the extrude index_finger and that is what the bone is called.

It is rolled to match the part, so the flat of the bone runs with the flat of the part and there is no arbitrary twist to undo on every one.

Select a bone first and the new ones hang off it, pointing away from it — which is also what decides which end of the part is the root, so place the palm bone before the fingers.

A part with no long axis, like a sphere or a cube, is skipped and named in the console rather than given a bone pointing nowhere in particular.

Pose the rig and watch it bend. A Pose button in the Rig panel — press it, drag a bone, and the mesh deforms with it, so a bad weight shows up as a crease instead of a number in a panel.

Reset Pose (or toggling Pose off) returns to the bind pose; nothing is saved. It is built on the same weights the export uses, so what you see is what compiles.

Assign bones from the Parts list. Right-click a part and pick Assign to bone — the same pinning the rig panel does, reachable from the body's side. An assigned part shows its bone in blue on the row.

An eraser. Hold Ctrl while you paint and the brush takes paint off instead of putting it on, back to the surface underneath.

The brush ring turns red while Ctrl is held, so you can see which one you are about to do before you press rather than after.

Erasing uses the brush you already have — the same size, strength and falloff — so a soft eraser fades out at its edge and a Constant one takes a hard bite.

An erase is a stroke like any other: one Ctrl+Z, saved into the .effigy, and still there after you edit a feature underneath it and the part rebuilds.

Ctrl is read once, when you press. Letting go halfway through does not turn the back half of the mark into paint.

Drag a box to select in a sketch. Press on empty space in the sketcher and drag: left to right takes only what is completely inside the box, right to left takes anything the box touches, the same two boxes Onshape has.

The box adds to what is already selected, so you can build a selection up out of several boxes. Clicking empty space still clears it.

A mirror tool. Select the geometry, arm Mirror, and click the line to reflect it across.

The copy is held symmetric to the original rather than just pasted, so dragging one half moves the other.

A point already sitting on the mirror line is shared rather than doubled, so a half profile drawn against the line closes into one region when it is mirrored.

The selection stays lit while a tool that uses it is armed, so Mirror and Offset are no longer aimed at something invisible.