Frequent tipster Leonid Nemirovsky sends us an AutoCAD tip for using the Geometric Constraint command in an unusual way.

"I use GeomConstraint to align blocks to construction lines in a drawing, or to align blocks to part of a drawing. First, insert the desired block, then draw a guideline where you want to align the block. Initiate the GeomConstraint command by typing, selecting, or whatever your preferred method is. Select Fix and choose an anchor point, then GeomConstraint and use the Parallel constraint. Pick the guideline, then part of your block. You will see that your block is now aligned with the guideline. Now that you can highlight the guideline with grips, grab one grip and move it around. The block will rotate around the anchor point."

Notes from Cadalyst Tip Patrol: Parametric constraints were added to AutoCAD's tool set in the 2010 release. Constraints control the geometric relationship between two dimensional objects; they can also control the dimensional aspect of objects. Although this tip demonstrates a more experimental use of constraints, they really shine in blocks, or when geometry needs to dictate other geometry. Constraints can also be useful when laying out a design. If you constrain certain aspects of your design, those design criteria will remain, ensuring that your design is correct and as it should be.