Set up a dynamic block with at stretch action. The length parameter has an increment of 2" from 2' to 12'
After placement, drag grip and get a dynamic input box with the overall width of the block. Type in a number (let's say 4') and the block jumps to 6' !! Now drag grip again, type in 3' at the dynamic input box and the length jumps to 2' !!
Any suggestions would be appreciated (block is attached below).
Thanks in advance