If you use the Hut inserts, you will have to find someone that has no clue about duck calls or duck hunting. Wives will buy them if they are pretty, but the hunter will not be as enthusiastic. Duck hunters have the money, they know what sounds good and demand it.
Knowing how to make your own inserts take a lot of time, and expense, a jig alone will cost you a $100 for a basic flat jig, and then you have too know how to tune and use a duck call. Figure on about 2 months to get the first good call made.
As to blanks, depending on how you decide to go with the inserts, either Louisiana style, Arkansas style or Reelfoot style of insert, the insert determines the size of blanks need. Arkansas inserts are the easiest and need a blank about a 4" long 1.25 square and the barrel will be 3" to 4" long and need to be about 1.5" square, depending on your design.
If you only want to make barrels, then buy Echo inserts, wives will buy them if they are pretty, some hunters will, but not a real duck hunter. You can find the Echo inserts at Echo Duck Calls under call parts listing, while you are there also order your bands for the barrels.
Unless you duck hunt and know how to use a duck call, you are wandering into a strange world. Duck hunters like to get up at 2AM, then sit in freezing weather until sunup to shoot a bird that tastes like liver.