CAD Administrator Michael O'Flaherty sent us a tip on how to measure distances and use them in the Extrude command.

"In our transition from designing in 2D to working in 3D, we had to convert quite a few three-view vendor drawings into 3D solid models. We often had to use the Distance command in one 2D view to determine how far to extrude a perimeter shown in another 2D view. The Extrude command does not have an option to select a point outside the z-axis to set the extrusion distance. By adding a dash of LISP, however, it's possible to use any two points, in any axis, to set an extrusion distance.
 
"To see how it works, create a circle in any plane in a drawing. Now draw a line of random length at any orientation (except along the z-axis of the circle's plane). Start the Extrude command and select the circle. Don't pick a point to complete the extrusion. Type (getdist), making sure to include the parentheses, and press Enter. You won't see a prompt at the command line, but using osnaps, snap to each end of the line. The circle will be extruded to a length equal to the length of the line, regardless of the orientation of the line. Using (getdist) to set a distance should work with any command that needs a distance for input."
 
Notes from Cadalyst Tip Patrol: This works great, and not just with the Extrude command, but with any command where you need to add a distance value — or at least every command that I tried out.