Take a look at this French HydroPlum seaplane. The plans only contain drawings of the bulkheads which may be scaled but they do not provide for any dimensions or off-sets etc. I cannot build if I cannot create accurate templates for the bulkheads etc. https://www.use.com/editset.pl?set=5734e2cdf654ebc8d720 These are the only seaplane plans in the world that would meet USA FAA 103 guidelines. I would enjoy learning how to use 3D CAD but I would want it to be inexpensive and EASY to learn and use. I have no idea what to use and I cannot afford ( time or money) to try out six of them to figure out which is best.