You can quickly make your own outline patterns from existing assembled wood parts with just a piece of white paper and an awl. Position the paper over the piece you want to duplicate and then rub around the edges. Remove the paper and lay it over your new wood. Next, following the creases, punch small holes into the wood with the awl. For straight lines, a hole at each end is sufficient. On curves, make holes closer together. Remove the paper, draw lines between the holes, and you are ready to cut.
If the sewer line or drain line for a home you are buying crosses another property, make sure there is a recorded easement that will permit access to maintain or repair it. Without an easement, you would have to hope for your neighbor’s cooperation, but you would not be able to count on it.