Here is a link to the video mentioned above
http://scrollsawworkshop.blogspot.com/2016/05/i-got-mail.html?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+ScrollsawWorkshop+%28Scrollsaw+Workshop%29
I use a quite a bit of 1/4" solid oak. Don't like Lowes boards & we don't have a Home Depot. Menards is "fair." Nearly impossible to find thin boards that aren't cupped. To solve that, I rip the board into strips, turn ever other one over and glue it back together.
Here is a place that ships flat lumber, but some of theirs is of a quality that you would not pick up at a store. Therefore, I only guess at how much extra to order. http://www.ocoochhardwoods.com/
For baltic birch, I have always been happy with this supplier. For complex pieces, I order "good both sides." That way if one side isn't perfect you have the option of flipping it over. http://www.sloanswoodshop.com/default.htm
Hope this helps Friend.
jerry