Hi. 

I have a project for clients who wish to have the cabinets made with double thickness birch ply. I need to draw this in polyboard (I only use 18mm and have it in stock). What’s the most efficient way to draw this up? Originally was spec at 18mm. So here is the file as is currently stands. All panels except the draw fronts need to have double thickness which I will laminate together. 

I had thought of just making the material 36mm in Polyboard but I want to be able to output that to Opticut without manually changing dimensions and potentially producing errors. 

Thanks!