To split polygons, select two vertices on a polygon to force an edge to be drawn between them. Vertices can also be selected in succession across polygons.

The Triple command subdivides any selected polygon with more than 3 vertices so that it consists only of triangle polygons. This can be very useful for preparing data to be saved in a format that does not support polygons with more than 3 vertices per polygon. It can also be useful for quickly breaking an n-gon down into triangles for similar export issues.

Found in the menu bar under Geometry > Polygon > Quadruple or, within the Topo tab toolbox, the Convert to Quadrangles command takes a series of vertices from an N-gon and creates a row of regular four sided (quadrangle) polygons. This is useful in creating quad strips, especially when re-topologizing a model. Using the Pen tool, lay down two opposing rows of vertices, then invoke the Convert to Quadrangles command and Modo automatically adds edges spanning between the opposing vertices, making quad polygons.

The Spin Quads command changes where your edges are attached within the geometry. For example, if you select two adjacent polys, this command spins them so that they attach to different points while leaving them in place. It changes the flow of your polygons while maintaining the surrounding mesh. Spin Edges does the same thing on an edge level, however, you can select one edge and spin it so that it bisects two polygons differently. Spin Quads only works with two polygons with the same edge number.

These tools are found on the Edge and Polygon tabs of the Modo Tools toolbar, under the Commands groups.

The Flip tool reverses the direction of selected polygons. Polygons are typically single sided and, as such, are only visible from one direction. The visible side is determined by the direction of the normal. The direction of a polygon is initially determined by the order in which its vertices were created, or selected, to make the polygon. The Flip tool effectively re-orders those vertices so that the polygon faces the opposite direction. For linear polygons, such as curves, the Flip tool reverses the order to force the curve to run the opposite direction.

The Align Polygons tool attempts to automatically make all polygons face the same direction. Use this when you have mesh geometry with polygons that have face normals facing both toward and away from the view. Align Polygons uses the first polygon you select as the model. It attempts to match the face normal direction of that polygon.

Found under the Commands section of the Polygons toolbox, the Make Curve Fill command converts a closed curve, or a series of connected curves, into a renderable flat polygon's surface. It works with both Bezier or Spline curve types and is especially useful for rendering simple vector graphics.

TIP:  Bezier curves for curve fill polygon types can be created by importing an .eps file, or by converting text to Beziers using the Convert Text to Beziers command. Curve fill polygons can also be created by turning on the Fill option on the Curve and Bezier tools.

The Merge Polygons option combines selected polygons into a single polygon of n-number of sides. Essentially, it removes all interior edges, so the multiple polygons can be treated as a single polygon.

This command can be found on the Polygon tab of the Modo Tools toolbar, in the Commands section on the Reduce pulldown. Expand the Commands section to see Reduce, then press the dropdown arrow and choose Merge, or on the menu bar choose Geometry > Polygon > Merge.

More complex selections merge as many polygons together as necessary to remove the target edges. If all the edges that use a vertex are deleted, then the vertex is deleted as well. It may be possible for you to specify selections that cannot all be consistently deleted. In that case the operation does the best that it can without leaving "spikes", which are edges entirely internal to a single polygon.

The Collapse command removes the selected element without destroying the integrity of the geometry. Any select polygon, edge, or vertex is deleted but no hole is left behind. Instead, the mesh heals, closing any gaps by merging the neighboring elements together.

Polygons: On the Polygons tab of the Modo Tools toolbar > Commands > Reduce > Collapse.

You can also select whatever geometry you wish to collapse and then choose Geometry > Collapse.

The Remove Polygon command deletes the selected polygons, completely removing them from the selected Mesh Item layer. The command is found within the Modeling tabs under the Polygon toolbox, or in the menu bar under Geometry > Remove. You can also simply press the Backspace key on the keyboard.

Unify Polygons lets you merge two polygons into a single polygon when you have two polygons that are in exactly the same space and the polygons share the same vertices.

To access Unify Polygons click the Polygon tab of the Modo Tools toolbar, then click the dropdown arrow next to Reduce and choose Unify. The selected polygons in the viewport are unified.

Precisely as the name implies, this command converts geometry created with the Text tool to Bezier curves. To use, type out a line of text using the Text tool, and then invoke the menu bar command Geometry > Convert Text to Bezier. Converted text becomes a collection of merged Bezier curves and can be further edited using the Bezier Curve tool. If desired, the Make Curve Fill command converts the curves back into render-able shapes.