Abstract: A method of making a pool liner, said pool liner having a floor section, a wall section and substantially invisible seams, said method comprising the steps of: providing a plurality of floor sheets wherein each sheet of said plurality of floor sheets has an edge; arranging said floor sheets in a pre-determined direction such that at least one edge of one sheet of said first plurality of floor sheets overlaps an adjacent edge of one sheet of said first plurality of floor sheets thereby creating a floor sheet to floor sheet intersection; heat welding said overlapping floor sheets at said floor sheet to floor sheet intersection; providing at least one wall sheet where said at least one wall sheet has an edge; placing said at least one wall sheet generally perpendicularly relative to said plurality of floor sheets; overlapping said at least one wall sheet with said floor sheets thereby creating a floor sheet to wall sheet intersection; and heat welding said at least one wall sheet with overlapping floor sheets at