So I bought some plans that teach you how to make a wood hot tub. Then I am going to make a wood fired heating system for it. Here is the question: I need to use "kiln dried" wood. This is so that when I fill it with water the wood swells up good and tight. Well I also want to save money doing this because a project like this is really not in the "necessary" stuff budget but more in the "fun-not needed" budget. Well on craigslist there is tons of wood that has been sitting indoors for 2 or more years. Some that have been sitting for 25 or so years! Would this stuff be as dry as needed or not? I assume kiln drying might just do what nature does but faster. No reason I can tell that wood that has been sitting wouldn't wick all the water out of itself. Next, the wood that has been recommended in order are Redwood, Douglas Fir, Cedar, White Oak, and Pine. Well on craigslist I can't get TOO picky. For example lots of cherry from time to time and such. Wouldn't really any wood work? Further, could I mix and match the wood?