Make2D is one of Rhino's weaker spots, but it is still an essential function for many people. Following are some bits of advice distilled from various discussions among the Pros on the Rhino newsgroup.
Make2D doesn't work with objects behind the camera – so make sure there are none selected for your scene. For views where the camera is inside the model, you may need to draw a plane that represents the camera location, split the model there, and delete/hide everything behind the camera.
Hide all objects that are already completely hidden behind others in the scene. One easy way to do this is to use SelVisible on your scene, then Invert the selection. Everything that selects can be hidden.
Hide (or simplify) objects with a lot of detail that will be tiny in the Make2D (for example screw threads). No need to calculate all those intersections and projections for something that will end up only being a few pixels in the final drawing.
Join all surfaces into polysurfaces as much as possible. Everywhere surface edges are concurrent, Rhino has to calculate two edges instead of one. See if there are overlaps.
Hide all curves if possible. They take longer to calculate. This is especially true with curves that are concurrent with surface edges. These are redundant anyway, so hide or delete them.
Check for bad objects (SelBadObjects) and fix if necessary!
If possible, ensure that the geometry included in the Make2D stays inside (does not touch) the view border at all. (This might be impossible for interiors.)
Lowering the
absolute unit tolerance by an order of magnitude (for example from .001 to .01) helps tremendously. Just remember that your resulting Make2D drawing will not be any more accurate than that. Also don't forget to set it back to the original tolerance later. For a discussion of what tolerances do in Rhino see
Understanding Tolerances.
And… your system also makes a difference.
Compiled by Mitch 8.02.09