AutoCAD block libraries can quickly become unwieldy due in part to the need to capture multiple options of what's effectively the same item. A common example of this is a table that is offered in 6 ft, 8 ft, and 10 ft varieties. Each of these requires it's own block simply because of the differing lengths. To help combat this, AutoCAD has long had the ability to create what it calls Dynamic Blocks. You've likely encountered a few Dynamic Blocks in at least a handful of drawings. The essence of Dynamic Blocks are that you can create just one block that can "dynamically" adjust based on some parameters you define.
Although the basic idea of what a Dynamic Block is hasn't been too difficult for most AutoCAD users to understand, how to create Dynamic Blocks has proven to be a different story entirely. Typically creating Dynamic Blocks has meant learning how to combine Actions and Parameters to accomplish something (like making a table longer). While these methods still apply for some Dynamic Blocks, a lesser known feature of the Parametric Drafting tools within AutoCAD is that they can double as Dynamic Block parameters. In the video above, I take a look at a simple L-desk where the secondary desk must be half the length of the primary desk. With Parametric Constraints, creating building this intelligence into a Dynamic Block is much less difficult than you would imagine. Have a look at the video above to learn how.