Looking for Help to Design a Freight Loading Sheet

I have come up with with a spreadsheet that shows an empty freight trailer.  Due to our palletized product being infinite amount of available sizes for product, I want to make a macro that would be able to draw an pallet with the dimensions I put in each time.  Right now I have it done with 2 macros that draw a predetermined pallet size.  Since our products vary in size each pallet going out will be different sizes and we are manually drawing on a sheet of paper how to best load the trailer.  

I have included the spreadsheet I have so far.  I would need to be able to put in any combination of dimensions for the pallet and press the button and it would produce the shape based on the scaling I have for the spreadsheet.  I would then be able to drag the shape and place it in the square (trailer bed) picture and move all these different shaped items around to I get the most efficient way to load each trailer leaving here.

Maybe macros aren’t the best way to do this.  I am using Excel 2016.  I am open to any suggestions.  

Any help on this is appreciated.  

Thanks!