I went to some of the warehouse places and saw that their luan sheets were miserable looking, i.e. warped, marked up, twisted and patched with fillers. Then I went to the lumberyard in town frequented by the builders who work on the the "big houses". They helped me pick through the stack to find the cleanest pieces, which I later found to be no problem to work with. From the outset, you should resolve to protect your pieces of luan from getting scratched and otherwise damaged when you handle it. Consider padding your work surfaces. Also, keep in mind that there is a finished side to the plywood. Plan your cutting so that the finished side faces out. This will take some planning. The beauty of door skins is the fact that they are so cheap. I would call this risk arbitrage. If you make a mistake,or find some terrible defect in the material, you can throw the stuff out or cut it up into little pieces to make Christmas ornaments without feeling that you've taken a big monetary loss.