1)The ground plane - Is it always a box or a rectangle.
2) I have drawn poly line sheet cutout and a box.I want to subtract box and poly line sheet.But If I try to subtract, I get the message - "Solid blank is unaffected by tool operation.So, I make the thickness of the box zero and then subtract and the problem i solved. Is it correct to make the thickness of the box as zero and then subtract.