Poplar is great for a box and I personally like a walnut paddle on it. I also like a walnut paddle on butternut, purple heart on on sassafrass, cedar, cherry, mahogany. I like walnut with a walnut paddle. Also I am fond of Osage Orange and catalpa, juniper for boxes. I stick to the rule that whatever paddle you use it should be at least as dense as the box it sets upon, and most generally a little denser.
GOOD LUCK, GOD BLESS, AND STAY SAFE !
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MOSSY OAK PRO STAFF