Above 1200 Sq/FT 30x40 shop design struggle

[Copthatlikeshisvise]

SO... I recently moved into a new house and it has a very nice pole barn 30deepx40wide shop. I put up a loft on one side i am struggling with a design layout. The shop will be used for building cars and general use. Im just not able to see the layout in my head any of you have a nice free layout designer app?

 

[BlueChip]

smartdraw.com was pretty easy to use when i laid out mine.