Just draw it out on paper.

If you want to try different arrangements make scale puppets and lay them on a scale sheet of plywood.

Even PowerPoint has scales available.

One inch equals one foot is a good size to play with on 8.5 x 11 paper.

Thanks for the reply. I know about cutting out scale templates, but it's so much faster to let a computer do the cutting and fitting.

Fortunately I don't work with wood that much.